Page table pages are batched-freed in release_pages on most
architectures. If we want to charge them to kmemcg (this is what is
done later in this series), we need to teach mem_cgroup_uncharge_list to
handle kmem pages.
Link: http://lkml.kernel.org/r/18d5c09e97f80074ed25b97a7d0f32b95d875717.1464079538.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, to charge a non-slab allocation to kmemcg one has to use
alloc_kmem_pages helper with __GFP_ACCOUNT flag. A page allocated with
this helper should finally be freed using free_kmem_pages, otherwise it
won't be uncharged.
This API suits its current users fine, but it turns out to be impossible
to use along with page reference counting, i.e. when an allocation is
supposed to be freed with put_page, as it is the case with pipe or unix
socket buffers.
To overcome this limitation, this patch moves charging/uncharging to
generic page allocator paths, i.e. to __alloc_pages_nodemask and
free_pages_prepare, and zaps alloc/free_kmem_pages helpers. This way,
one can use any of the available page allocation functions to get the
allocated page charged to kmemcg - it's enough to pass __GFP_ACCOUNT,
just like in case of kmalloc and friends. A charged page will be
automatically uncharged on free.
To make it possible, we need to mark pages charged to kmemcg somehow.
To avoid introducing a new page flag, we make use of page->_mapcount for
marking such pages. Since pages charged to kmemcg are not supposed to
be mapped to userspace, it should work just fine. There are other
(ab)users of page->_mapcount - buddy and balloon pages - but we don't
conflict with them.
In case kmemcg is compiled out or not used at runtime, this patch
introduces no overhead to generic page allocator paths. If kmemcg is
used, it will be plus one gfp flags check on alloc and plus one
page->_mapcount check on free, which shouldn't hurt performance, because
the data accessed are hot.
Link: http://lkml.kernel.org/r/a9736d856f895bcb465d9f257b54efe32eda6f99.1464079538.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Handle memcg_kmem_enabled check out to the caller. This reduces the
number of function definitions making the code easier to follow. At
the same time it doesn't result in code bloat, because all of these
functions are used only in one or two places.
- Move __GFP_ACCOUNT check to the caller as well so that one wouldn't
have to dive deep into memcg implementation to see which allocations
are charged and which are not.
- Refresh comments.
Link: http://lkml.kernel.org/r/52882a28b542c1979fd9a033b4dc8637fc347399.1464079537.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This allows an arch which needs to do special handing with respect to
different page size when flushing tlb to implement the same in mmu
gather.
Link: http://lkml.kernel.org/r/1465049193-22197-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This updates the generic and arch specific implementation to return true
if we need to do a tlb flush. That means if a __tlb_remove_page
indicate a flush is needed, the page we try to remove need to be tracked
and added again after the flush. We need to track it because we have
already update the pte to none and we can't just loop back.
This change is done to enable us to do a tlb_flush when we try to flush
a range that consists of different page sizes. For architectures like
ppc64, we can do a range based tlb flush and we need to track page size
for that. When we try to remove a huge page, we will force a tlb flush
and starts a new mmu gather.
[aneesh.kumar@linux.vnet.ibm.com: mm-change-the-interface-for-__tlb_remove_page-v3]
Link: http://lkml.kernel.org/r/1465049193-22197-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1464860389-29019-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For hugetlb like THP (and unlike regular page), we do tlb flush after
dropping ptl. Because of the above, we don't need to track force_flush
like we do now. Instead we can simply call tlb_remove_page() which will
do the flush if needed.
No functionality change in this patch.
Link: http://lkml.kernel.org/r/1465049193-22197-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
split_huge_pmd() doesn't guarantee that the pmd is normal pmd pointing
to pte entries, which can be checked with pmd_trans_unstable(). Some
callers make this assertion and some do it differently and some not, so
let's do it in a unified manner.
Link: http://lkml.kernel.org/r/1464741400-12143-1-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When there is an isolated_page, post_alloc_hook() is called with page
but __free_pages() is called with isolated_page. Since they are the
same so no problem but it's very confusing. To reduce it, this patch
changes isolated_page to boolean type and uses page variable
consistently.
Link: http://lkml.kernel.org/r/1466150259-27727-10-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch is motivated from Hugh and Vlastimil's concern [1].
There are two ways to get freepage from the allocator. One is using
normal memory allocation API and the other is __isolate_free_page()
which is internally used for compaction and pageblock isolation. Later
usage is rather tricky since it doesn't do whole post allocation
processing done by normal API.
One problematic thing I already know is that poisoned page would not be
checked if it is allocated by __isolate_free_page(). Perhaps, there
would be more.
We could add more debug logic for allocated page in the future and this
separation would cause more problem. I'd like to fix this situation at
this time. Solution is simple. This patch commonize some logic for
newly allocated page and uses it on all sites. This will solve the
problem.
[1] http://marc.info/?i=alpine.LSU.2.11.1604270029350.7066%40eggly.anvils%3E
[iamjoonsoo.kim@lge.com: mm-page_alloc-introduce-post-allocation-processing-on-page-allocator-v3]
Link: http://lkml.kernel.org/r/1464230275-25791-7-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1466150259-27727-9-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1464230275-25791-7-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, we store each page's allocation stacktrace on corresponding
page_ext structure and it requires a lot of memory. This causes the
problem that memory tight system doesn't work well if page_owner is
enabled. Moreover, even with this large memory consumption, we cannot
get full stacktrace because we allocate memory at boot time and just
maintain 8 stacktrace slots to balance memory consumption. We could
increase it to more but it would make system unusable or change system
behaviour.
To solve the problem, this patch uses stackdepot to store stacktrace.
It obviously provides memory saving but there is a drawback that
stackdepot could fail.
stackdepot allocates memory at runtime so it could fail if system has
not enough memory. But, most of allocation stack are generated at very
early time and there are much memory at this time. So, failure would
not happen easily. And, one failure means that we miss just one page's
allocation stacktrace so it would not be a big problem. In this patch,
when memory allocation failure happens, we store special stracktrace
handle to the page that is failed to save stacktrace. With it, user can
guess memory usage properly even if failure happens.
Memory saving looks as following. (4GB memory system with page_owner)
(before the patch -> after the patch)
static allocation:
92274688 bytes -> 25165824 bytes
dynamic allocation after boot + kernel build:
0 bytes -> 327680 bytes
total:
92274688 bytes -> 25493504 bytes
72% reduction in total.
Note that implementation looks complex than someone would imagine
because there is recursion issue. stackdepot uses page allocator and
page_owner is called at page allocation. Using stackdepot in page_owner
could re-call page allcator and then page_owner. That is a recursion.
To detect and avoid it, whenever we obtain stacktrace, recursion is
checked and page_owner is set to dummy information if found. Dummy
information means that this page is allocated for page_owner feature
itself (such as stackdepot) and it's understandable behavior for user.
[iamjoonsoo.kim@lge.com: mm-page_owner-use-stackdepot-to-store-stacktrace-v3]
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1466150259-27727-7-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
split_page() calls set_page_owner() to set up page_owner to each pages.
But, it has a drawback that head page and the others have different
stacktrace because callsite of set_page_owner() is slightly differnt.
To avoid this problem, this patch copies head page's page_owner to the
others. It needs to introduce new function, split_page_owner() but it
also remove the other function, get_page_owner_gfp() so looks good to
do.
Link: http://lkml.kernel.org/r/1464230275-25791-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, copy_page_owner() doesn't copy all the owner information. It
skips last_migrate_reason because copy_page_owner() is used for
migration and it will be properly set soon. But, following patch will
use copy_page_owner() and this skip will cause the problem that
allocated page has uninitialied last_migrate_reason. To prevent it,
this patch also copy last_migrate_reason in copy_page_owner().
Link: http://lkml.kernel.org/r/1464230275-25791-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's not necessary to initialized page_owner with holding the zone lock.
It would cause more contention on the zone lock although it's not a big
problem since it is just debug feature. But, it is better than before
so do it. This is also preparation step to use stackdepot in page owner
feature. Stackdepot allocates new pages when there is no reserved space
and holding the zone lock in this case will cause deadlock.
Link: http://lkml.kernel.org/r/1464230275-25791-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't need to split freepages with holding the zone lock. It will
cause more contention on zone lock so not desirable.
[rientjes@google.com: if __isolate_free_page() fails, avoid adding to freelist so we don't call map_pages() with it]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211447001.43430@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Static check warns using tag as bit shifter. It doesn't break current
working but not good for redability. Let's use OBJ_TAG_BIT as bit
shifter instead of OBJ_ALLOCATED_TAG.
Link: http://lkml.kernel.org/r/20160607045146.GF26230@bbox
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch introduces run-time migration feature for zspage.
For migration, VM uses page.lru field so it would be better to not use
page.next field which is unified with page.lru for own purpose. For
that, firstly, we can get first object offset of the page via runtime
calculation instead of using page.index so we can use page.index as link
for page chaining instead of page.next.
In case of huge object, it stores handle to page.index instead of next
link of page chaining because huge object doesn't need to next link for
page chaining. So get_next_page need to identify huge object to return
NULL. For it, this patch uses PG_owner_priv_1 flag of the page flag.
For migration, it supports three functions
* zs_page_isolate
It isolates a zspage which includes a subpage VM want to migrate from
class so anyone cannot allocate new object from the zspage.
We could try to isolate a zspage by the number of subpage so subsequent
isolation trial of other subpage of the zpsage shouldn't fail. For
that, we introduce zspage.isolated count. With that, zs_page_isolate
can know whether zspage is already isolated or not for migration so if
it is isolated for migration, subsequent isolation trial can be
successful without trying further isolation.
* zs_page_migrate
First of all, it holds write-side zspage->lock to prevent migrate other
subpage in zspage. Then, lock all objects in the page VM want to
migrate. The reason we should lock all objects in the page is due to
race between zs_map_object and zs_page_migrate.
zs_map_object zs_page_migrate
pin_tag(handle)
obj = handle_to_obj(handle)
obj_to_location(obj, &page, &obj_idx);
write_lock(&zspage->lock)
if (!trypin_tag(handle))
goto unpin_object
zspage = get_zspage(page);
read_lock(&zspage->lock);
If zs_page_migrate doesn't do trypin_tag, zs_map_object's page can be
stale by migration so it goes crash.
If it locks all of objects successfully, it copies content from old page
to new one, finally, create new zspage chain with new page. And if it's
last isolated subpage in the zspage, put the zspage back to class.
* zs_page_putback
It returns isolated zspage to right fullness_group list if it fails to
migrate a page. If it find a zspage is ZS_EMPTY, it queues zspage
freeing to workqueue. See below about async zspage freeing.
This patch introduces asynchronous zspage free. The reason to need it
is we need page_lock to clear PG_movable but unfortunately, zs_free path
should be atomic so the apporach is try to grab page_lock. If it got
page_lock of all of pages successfully, it can free zspage immediately.
Otherwise, it queues free request and free zspage via workqueue in
process context.
If zs_free finds the zspage is isolated when it try to free zspage, it
delays the freeing until zs_page_putback finds it so it will free free
the zspage finally.
In this patch, we expand fullness_list from ZS_EMPTY to ZS_FULL. First
of all, it will use ZS_EMPTY list for delay freeing. And with adding
ZS_FULL list, it makes to identify whether zspage is isolated or not via
list_empty(&zspage->list) test.
[minchan@kernel.org: zsmalloc: keep first object offset in struct page]
Link: http://lkml.kernel.org/r/1465788015-23195-1-git-send-email-minchan@kernel.org
[minchan@kernel.org: zsmalloc: zspage sanity check]
Link: http://lkml.kernel.org/r/20160603010129.GC3304@bbox
Link: http://lkml.kernel.org/r/1464736881-24886-12-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Zsmalloc stores first free object's <PFN, obj_idx> position into freeobj
in each zspage. If we change it with index from first_page instead of
position, it makes page migration simple because we don't need to
correct other entries for linked list if a page is migrated out.
Link: http://lkml.kernel.org/r/1464736881-24886-11-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, putback_zspage does free zspage under class->lock if fullness
become ZS_EMPTY but it makes trouble to implement locking scheme for new
zspage migration. So, this patch is to separate free_zspage from
putback_zspage and free zspage out of class->lock which is preparation
for zspage migration.
Link: http://lkml.kernel.org/r/1464736881-24886-10-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have squeezed meta data of zspage into first page's descriptor. So,
to get meta data from subpage, we should get first page first of all.
But it makes trouble to implment page migration feature of zsmalloc
because any place where to get first page from subpage can be raced with
first page migration. IOW, first page it got could be stale. For
preventing it, I have tried several approahces but it made code
complicated so finally, I concluded to separate metadata from first
page. Of course, it consumes more memory. IOW, 16bytes per zspage on
32bit at the moment. It means we lost 1% at *worst case*(40B/4096B)
which is not bad I think at the cost of maintenance.
Link: http://lkml.kernel.org/r/1464736881-24886-9-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For page migration, we need to create page chain of zspage dynamically
so this patch factors it out from alloc_zspage.
Link: http://lkml.kernel.org/r/1464736881-24886-8-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Upcoming patch will change how to encode zspage meta so for easy review,
this patch wraps code to access metadata as accessor.
Link: http://lkml.kernel.org/r/1464736881-24886-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use kernel standard bit spin-lock instead of custom mess. Even, it has
a bug which doesn't disable preemption. The reason we don't have any
problem is that we have used it during preemption disable section by
class->lock spinlock. So no need to go to stable.
Link: http://lkml.kernel.org/r/1464736881-24886-6-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every zspage in a size_class has same number of max objects so we could
move it to a size_class.
Link: http://lkml.kernel.org/r/1464736881-24886-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, VM has a feature to migrate non-lru movable pages so balloon
doesn't need custom migration hooks in migrate.c and compaction.c.
Instead, this patch implements the page->mapping->a_ops->
{isolate|migrate|putback} functions.
With that, we could remove hooks for ballooning in general migration
functions and make balloon compaction simple.
[akpm@linux-foundation.org: compaction.h requires that the includer first include node.h]
Link: http://lkml.kernel.org/r/1464736881-24886-4-git-send-email-minchan@kernel.org
Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have allowed migration for only LRU pages until now and it was enough
to make high-order pages. But recently, embedded system(e.g., webOS,
android) uses lots of non-movable pages(e.g., zram, GPU memory) so we
have seen several reports about troubles of small high-order allocation.
For fixing the problem, there were several efforts (e,g,. enhance
compaction algorithm, SLUB fallback to 0-order page, reserved memory,
vmalloc and so on) but if there are lots of non-movable pages in system,
their solutions are void in the long run.
So, this patch is to support facility to change non-movable pages with
movable. For the feature, this patch introduces functions related to
migration to address_space_operations as well as some page flags.
If a driver want to make own pages movable, it should define three
functions which are function pointers of struct
address_space_operations.
1. bool (*isolate_page) (struct page *page, isolate_mode_t mode);
What VM expects on isolate_page function of driver is to return *true*
if driver isolates page successfully. On returing true, VM marks the
page as PG_isolated so concurrent isolation in several CPUs skip the
page for isolation. If a driver cannot isolate the page, it should
return *false*.
Once page is successfully isolated, VM uses page.lru fields so driver
shouldn't expect to preserve values in that fields.
2. int (*migratepage) (struct address_space *mapping,
struct page *newpage, struct page *oldpage, enum migrate_mode);
After isolation, VM calls migratepage of driver with isolated page. The
function of migratepage is to move content of the old page to new page
and set up fields of struct page newpage. Keep in mind that you should
indicate to the VM the oldpage is no longer movable via
__ClearPageMovable() under page_lock if you migrated the oldpage
successfully and returns 0. If driver cannot migrate the page at the
moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page
migration in a short time because VM interprets -EAGAIN as "temporal
migration failure". On returning any error except -EAGAIN, VM will give
up the page migration without retrying in this time.
Driver shouldn't touch page.lru field VM using in the functions.
3. void (*putback_page)(struct page *);
If migration fails on isolated page, VM should return the isolated page
to the driver so VM calls driver's putback_page with migration failed
page. In this function, driver should put the isolated page back to the
own data structure.
4. non-lru movable page flags
There are two page flags for supporting non-lru movable page.
* PG_movable
Driver should use the below function to make page movable under
page_lock.
void __SetPageMovable(struct page *page, struct address_space *mapping)
It needs argument of address_space for registering migration family
functions which will be called by VM. Exactly speaking, PG_movable is
not a real flag of struct page. Rather than, VM reuses page->mapping's
lower bits to represent it.
#define PAGE_MAPPING_MOVABLE 0x2
page->mapping = page->mapping | PAGE_MAPPING_MOVABLE;
so driver shouldn't access page->mapping directly. Instead, driver
should use page_mapping which mask off the low two bits of page->mapping
so it can get right struct address_space.
For testing of non-lru movable page, VM supports __PageMovable function.
However, it doesn't guarantee to identify non-lru movable page because
page->mapping field is unified with other variables in struct page. As
well, if driver releases the page after isolation by VM, page->mapping
doesn't have stable value although it has PAGE_MAPPING_MOVABLE (Look at
__ClearPageMovable). But __PageMovable is cheap to catch whether page
is LRU or non-lru movable once the page has been isolated. Because LRU
pages never can have PAGE_MAPPING_MOVABLE in page->mapping. It is also
good for just peeking to test non-lru movable pages before more
expensive checking with lock_page in pfn scanning to select victim.
For guaranteeing non-lru movable page, VM provides PageMovable function.
Unlike __PageMovable, PageMovable functions validates page->mapping and
mapping->a_ops->isolate_page under lock_page. The lock_page prevents
sudden destroying of page->mapping.
Driver using __SetPageMovable should clear the flag via
__ClearMovablePage under page_lock before the releasing the page.
* PG_isolated
To prevent concurrent isolation among several CPUs, VM marks isolated
page as PG_isolated under lock_page. So if a CPU encounters PG_isolated
non-lru movable page, it can skip it. Driver doesn't need to manipulate
the flag because VM will set/clear it automatically. Keep in mind that
if driver sees PG_isolated page, it means the page have been isolated by
VM so it shouldn't touch page.lru field. PG_isolated is alias with
PG_reclaim flag so driver shouldn't use the flag for own purpose.
[opensource.ganesh@gmail.com: mm/compaction: remove local variable is_lru]
Link: http://lkml.kernel.org/r/20160618014841.GA7422@leo-test
Link: http://lkml.kernel.org/r/1464736881-24886-3-git-send-email-minchan@kernel.org
Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: John Einar Reitan <john.reitan@foss.arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently, I got many reports about perfermance degradation in embedded
system(Android mobile phone, webOS TV and so on) and easy fork fail.
The problem was fragmentation caused by zram and GPU driver mainly.
With memory pressure, their pages were spread out all of pageblock and
it cannot be migrated with current compaction algorithm which supports
only LRU pages. In the end, compaction cannot work well so reclaimer
shrinks all of working set pages. It made system very slow and even to
fail to fork easily which requires order-[2 or 3] allocations.
Other pain point is that they cannot use CMA memory space so when OOM
kill happens, I can see many free pages in CMA area, which is not memory
efficient. In our product which has big CMA memory, it reclaims zones
too exccessively to allocate GPU and zram page although there are lots
of free space in CMA so system becomes very slow easily.
To solve these problem, this patch tries to add facility to migrate
non-lru pages via introducing new functions and page flags to help
migration.
struct address_space_operations {
..
..
bool (*isolate_page)(struct page *, isolate_mode_t);
void (*putback_page)(struct page *);
..
}
new page flags
PG_movable
PG_isolated
For details, please read description in "mm: migrate: support non-lru
movable page migration".
Originally, Gioh Kim had tried to support this feature but he moved so I
took over the work. I took many code from his work and changed a little
bit and Konstantin Khlebnikov helped Gioh a lot so he should deserve to
have many credit, too.
And I should mention Chulmin who have tested this patchset heavily so I
can find many bugs from him. :)
Thanks, Gioh, Konstantin and Chulmin!
This patchset consists of five parts.
1. clean up migration
mm: use put_page to free page instead of putback_lru_page
2. add non-lru page migration feature
mm: migrate: support non-lru movable page migration
3. rework KVM memory-ballooning
mm: balloon: use general non-lru movable page feature
4. zsmalloc refactoring for preparing page migration
zsmalloc: keep max_object in size_class
zsmalloc: use bit_spin_lock
zsmalloc: use accessor
zsmalloc: factor page chain functionality out
zsmalloc: introduce zspage structure
zsmalloc: separate free_zspage from putback_zspage
zsmalloc: use freeobj for index
5. zsmalloc page migration
zsmalloc: page migration support
zram: use __GFP_MOVABLE for memory allocation
This patch (of 12):
Procedure of page migration is as follows:
First of all, it should isolate a page from LRU and try to migrate the
page. If it is successful, it releases the page for freeing.
Otherwise, it should put the page back to LRU list.
For LRU pages, we have used putback_lru_page for both freeing and
putback to LRU list. It's okay because put_page is aware of LRU list so
if it releases last refcount of the page, it removes the page from LRU
list. However, It makes unnecessary operations (e.g., lru_cache_add,
pagevec and flags operations. It would be not significant but no worth
to do) and harder to support new non-lru page migration because put_page
isn't aware of non-lru page's data structure.
To solve the problem, we can add new hook in put_page with PageMovable
flags check but it can increase overhead in hot path and needs new
locking scheme to stabilize the flag check with put_page.
So, this patch cleans it up to divide two semantic(ie, put and putback).
If migration is successful, use put_page instead of putback_lru_page and
use putback_lru_page only on failure. That makes code more readable and
doesn't add overhead in put_page.
Comment from Vlastimil
"Yeah, and compaction (perhaps also other migration users) has to drain
the lru pvec... Getting rid of this stuff is worth even by itself."
Link: http://lkml.kernel.org/r/1464736881-24886-2-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's a part of oom context just like allocation order and nodemask, so
let's move it to oom_control instead of passing it in the argument list.
Link: http://lkml.kernel.org/r/40e03fd7aaf1f55c75d787128d6d17c5a71226c2.1464358556.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Not used since oom_lock was instroduced.
Link: http://lkml.kernel.org/r/1464358093-22663-1-git-send-email-vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When memory is onlined, we are only able to rezone from ZONE_MOVABLE to
ZONE_KERNEL, or from (ZONE_MOVABLE - 1) to ZONE_MOVABLE.
To be more flexible, use the following criteria instead; to online
memory from zone X into zone Y,
* Any zones between X and Y must be unused.
* If X is lower than Y, the onlined memory must lie at the end of X.
* If X is higher than Y, the onlined memory must lie at the start of X.
Add zone_can_shift() to make this determination.
Link: http://lkml.kernel.org/r/1462816419-4479-3-git-send-email-arbab@linux.vnet.ibm.com
Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Reviewd-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add move_pfn_range(), a wrapper to call move_pfn_range_left() or
move_pfn_range_right().
No functional change. This will be utilized by a later patch.
Link: http://lkml.kernel.org/r/1462816419-4479-2-git-send-email-arbab@linux.vnet.ibm.com
Signed-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Zhang Zhen <zhenzhang.zhang@huawei.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As a part of memory initialisation the architecture passes an array to
free_area_init_nodes() which specifies the max PFN of each memory zone.
This array is not necessarily monotonic (due to unused zones) so this
array is parsed to build monotonic lists of the min and max PFN for each
zone. ZONE_MOVABLE is special cased here as its limits are managed by
the mm subsystem rather than the architecture. Unfortunately, this
special casing is broken when ZONE_MOVABLE is the not the last zone in
the zone list. The core of the issue is:
if (i == ZONE_MOVABLE)
continue;
arch_zone_lowest_possible_pfn[i] =
arch_zone_highest_possible_pfn[i-1];
As ZONE_MOVABLE is skipped the lowest_possible_pfn of the next zone will
be set to zero. This patch fixes this bug by adding explicitly tracking
where the next zone should start rather than relying on the contents
arch_zone_highest_possible_pfn[].
Thie is low priority. To get bitten by this you need to enable a zone
that appears after ZONE_MOVABLE in the zone_type enum. As far as I can
tell this means running a kernel with ZONE_DEVICE or ZONE_CMA enabled,
so I can't see this affecting too many people.
I only noticed this because I've been fiddling with ZONE_DEVICE on
powerpc and 4.6 broke my test kernel. This bug, in conjunction with the
changes in Taku Izumi's kernelcore=mirror patch (d91749c1dd) and
powerpc being the odd architecture which initialises max_zone_pfn[] to
~0ul instead of 0 caused all of system memory to be placed into
ZONE_DEVICE at boot, followed a panic since device memory cannot be used
for kernel allocations. I've already submitted a patch to fix the
powerpc specific bits, but I figured this should be fixed too.
Link: http://lkml.kernel.org/r/1462435033-15601-1-git-send-email-oohall@gmail.com
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It seems like this parameter has never been used since being introduced
by 90254a6583 ("memcg: clean up move charge"). Not a big deal because
I assume the function would get inlined into the caller anyway but why
not get rid of it.
[mhocko@suse.com: wrote changelog]
Link: http://lkml.kernel.org/r/20160525151831.GJ20132@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1464145026-26693-1-git-send-email-roy.qing.li@gmail.com
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using list_move() instead of list_del() + list_add() to avoid needlessly
poisoning the next and prev values.
Link: http://lkml.kernel.org/r/1468929772-9174-1-git-send-email-weiyj_lk@163.com
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both SLAB and SLUB BUG() when a caller provides an invalid gfp_mask.
This is a rather harsh way to announce a non-critical issue. Allocator
is free to ignore invalid flags. Let's simply replace BUG() by
dump_stack to tell the offender and fixup the mask to move on with the
allocation request.
This is an example for kmalloc(GFP_KERNEL|__GFP_HIGHMEM) from a test
module:
Unexpected gfp: 0x2 (__GFP_HIGHMEM). Fixing up to gfp: 0x24000c0 (GFP_KERNEL). Fix your code!
CPU: 0 PID: 2916 Comm: insmod Tainted: G O 4.6.0-slabgfp2-00002-g4cdfc2ef4892-dirty #936
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
Call Trace:
dump_stack+0x67/0x90
cache_alloc_refill+0x201/0x617
kmem_cache_alloc_trace+0xa7/0x24a
? 0xffffffffa0005000
mymodule_init+0x20/0x1000 [test_slab]
do_one_initcall+0xe7/0x16c
? rcu_read_lock_sched_held+0x61/0x69
? kmem_cache_alloc_trace+0x197/0x24a
do_init_module+0x5f/0x1d9
load_module+0x1a3d/0x1f21
? retint_kernel+0x2d/0x2d
SyS_init_module+0xe8/0x10e
? SyS_init_module+0xe8/0x10e
do_syscall_64+0x68/0x13f
entry_SYSCALL64_slow_path+0x25/0x25
Link: http://lkml.kernel.org/r/1465548200-11384-2-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk offers %pGg for quite some time so let's use it to get a human
readable list of invalid flags.
The original output would be
[ 429.191962] gfp: 2
after the change
[ 429.191962] Unexpected gfp: 0x2 (__GFP_HIGHMEM)
Link: http://lkml.kernel.org/r/1465548200-11384-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Implements freelist randomization for the SLUB allocator. It was
previous implemented for the SLAB allocator. Both use the same
configuration option (CONFIG_SLAB_FREELIST_RANDOM).
The list is randomized during initialization of a new set of pages. The
order on different freelist sizes is pre-computed at boot for
performance. Each kmem_cache has its own randomized freelist.
This security feature reduces the predictability of the kernel SLUB
allocator against heap overflows rendering attacks much less stable.
For example these attacks exploit the predictability of the heap:
- Linux Kernel CAN SLUB overflow (https://goo.gl/oMNWkU)
- Exploiting Linux Kernel Heap corruptions (http://goo.gl/EXLn95)
Performance results:
slab_test impact is between 3% to 4% on average for 100000 attempts
without smp. It is a very focused testing, kernbench show the overall
impact on the system is way lower.
Before:
Single thread testing
=====================
1. Kmalloc: Repeatedly allocate then free test
100000 times kmalloc(8) -> 49 cycles kfree -> 77 cycles
100000 times kmalloc(16) -> 51 cycles kfree -> 79 cycles
100000 times kmalloc(32) -> 53 cycles kfree -> 83 cycles
100000 times kmalloc(64) -> 62 cycles kfree -> 90 cycles
100000 times kmalloc(128) -> 81 cycles kfree -> 97 cycles
100000 times kmalloc(256) -> 98 cycles kfree -> 121 cycles
100000 times kmalloc(512) -> 95 cycles kfree -> 122 cycles
100000 times kmalloc(1024) -> 96 cycles kfree -> 126 cycles
100000 times kmalloc(2048) -> 115 cycles kfree -> 140 cycles
100000 times kmalloc(4096) -> 149 cycles kfree -> 171 cycles
2. Kmalloc: alloc/free test
100000 times kmalloc(8)/kfree -> 70 cycles
100000 times kmalloc(16)/kfree -> 70 cycles
100000 times kmalloc(32)/kfree -> 70 cycles
100000 times kmalloc(64)/kfree -> 70 cycles
100000 times kmalloc(128)/kfree -> 70 cycles
100000 times kmalloc(256)/kfree -> 69 cycles
100000 times kmalloc(512)/kfree -> 70 cycles
100000 times kmalloc(1024)/kfree -> 73 cycles
100000 times kmalloc(2048)/kfree -> 72 cycles
100000 times kmalloc(4096)/kfree -> 71 cycles
After:
Single thread testing
=====================
1. Kmalloc: Repeatedly allocate then free test
100000 times kmalloc(8) -> 57 cycles kfree -> 78 cycles
100000 times kmalloc(16) -> 61 cycles kfree -> 81 cycles
100000 times kmalloc(32) -> 76 cycles kfree -> 93 cycles
100000 times kmalloc(64) -> 83 cycles kfree -> 94 cycles
100000 times kmalloc(128) -> 106 cycles kfree -> 107 cycles
100000 times kmalloc(256) -> 118 cycles kfree -> 117 cycles
100000 times kmalloc(512) -> 114 cycles kfree -> 116 cycles
100000 times kmalloc(1024) -> 115 cycles kfree -> 118 cycles
100000 times kmalloc(2048) -> 147 cycles kfree -> 131 cycles
100000 times kmalloc(4096) -> 214 cycles kfree -> 161 cycles
2. Kmalloc: alloc/free test
100000 times kmalloc(8)/kfree -> 66 cycles
100000 times kmalloc(16)/kfree -> 66 cycles
100000 times kmalloc(32)/kfree -> 66 cycles
100000 times kmalloc(64)/kfree -> 66 cycles
100000 times kmalloc(128)/kfree -> 65 cycles
100000 times kmalloc(256)/kfree -> 67 cycles
100000 times kmalloc(512)/kfree -> 67 cycles
100000 times kmalloc(1024)/kfree -> 64 cycles
100000 times kmalloc(2048)/kfree -> 67 cycles
100000 times kmalloc(4096)/kfree -> 67 cycles
Kernbench, before:
Average Optimal load -j 12 Run (std deviation):
Elapsed Time 101.873 (1.16069)
User Time 1045.22 (1.60447)
System Time 88.969 (0.559195)
Percent CPU 1112.9 (13.8279)
Context Switches 189140 (2282.15)
Sleeps 99008.6 (768.091)
After:
Average Optimal load -j 12 Run (std deviation):
Elapsed Time 102.47 (0.562732)
User Time 1045.3 (1.34263)
System Time 88.311 (0.342554)
Percent CPU 1105.8 (6.49444)
Context Switches 189081 (2355.78)
Sleeps 99231.5 (800.358)
Link: http://lkml.kernel.org/r/1464295031-26375-3-git-send-email-thgarnie@google.com
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel heap allocators are using a sequential freelist making their
allocation predictable. This predictability makes kernel heap overflow
easier to exploit. An attacker can careful prepare the kernel heap to
control the following chunk overflowed.
For example these attacks exploit the predictability of the heap:
- Linux Kernel CAN SLUB overflow (https://goo.gl/oMNWkU)
- Exploiting Linux Kernel Heap corruptions (http://goo.gl/EXLn95)
***Problems that needed solving:
- Randomize the Freelist (singled linked) used in the SLUB allocator.
- Ensure good performance to encourage usage.
- Get best entropy in early boot stage.
***Parts:
- 01/02 Reorganize the SLAB Freelist randomization to share elements
with the SLUB implementation.
- 02/02 The SLUB Freelist randomization implementation. Similar approach
than the SLAB but tailored to the singled freelist used in SLUB.
***Performance data:
slab_test impact is between 3% to 4% on average for 100000 attempts
without smp. It is a very focused testing, kernbench show the overall
impact on the system is way lower.
Before:
Single thread testing
=====================
1. Kmalloc: Repeatedly allocate then free test
100000 times kmalloc(8) -> 49 cycles kfree -> 77 cycles
100000 times kmalloc(16) -> 51 cycles kfree -> 79 cycles
100000 times kmalloc(32) -> 53 cycles kfree -> 83 cycles
100000 times kmalloc(64) -> 62 cycles kfree -> 90 cycles
100000 times kmalloc(128) -> 81 cycles kfree -> 97 cycles
100000 times kmalloc(256) -> 98 cycles kfree -> 121 cycles
100000 times kmalloc(512) -> 95 cycles kfree -> 122 cycles
100000 times kmalloc(1024) -> 96 cycles kfree -> 126 cycles
100000 times kmalloc(2048) -> 115 cycles kfree -> 140 cycles
100000 times kmalloc(4096) -> 149 cycles kfree -> 171 cycles
2. Kmalloc: alloc/free test
100000 times kmalloc(8)/kfree -> 70 cycles
100000 times kmalloc(16)/kfree -> 70 cycles
100000 times kmalloc(32)/kfree -> 70 cycles
100000 times kmalloc(64)/kfree -> 70 cycles
100000 times kmalloc(128)/kfree -> 70 cycles
100000 times kmalloc(256)/kfree -> 69 cycles
100000 times kmalloc(512)/kfree -> 70 cycles
100000 times kmalloc(1024)/kfree -> 73 cycles
100000 times kmalloc(2048)/kfree -> 72 cycles
100000 times kmalloc(4096)/kfree -> 71 cycles
After:
Single thread testing
=====================
1. Kmalloc: Repeatedly allocate then free test
100000 times kmalloc(8) -> 57 cycles kfree -> 78 cycles
100000 times kmalloc(16) -> 61 cycles kfree -> 81 cycles
100000 times kmalloc(32) -> 76 cycles kfree -> 93 cycles
100000 times kmalloc(64) -> 83 cycles kfree -> 94 cycles
100000 times kmalloc(128) -> 106 cycles kfree -> 107 cycles
100000 times kmalloc(256) -> 118 cycles kfree -> 117 cycles
100000 times kmalloc(512) -> 114 cycles kfree -> 116 cycles
100000 times kmalloc(1024) -> 115 cycles kfree -> 118 cycles
100000 times kmalloc(2048) -> 147 cycles kfree -> 131 cycles
100000 times kmalloc(4096) -> 214 cycles kfree -> 161 cycles
2. Kmalloc: alloc/free test
100000 times kmalloc(8)/kfree -> 66 cycles
100000 times kmalloc(16)/kfree -> 66 cycles
100000 times kmalloc(32)/kfree -> 66 cycles
100000 times kmalloc(64)/kfree -> 66 cycles
100000 times kmalloc(128)/kfree -> 65 cycles
100000 times kmalloc(256)/kfree -> 67 cycles
100000 times kmalloc(512)/kfree -> 67 cycles
100000 times kmalloc(1024)/kfree -> 64 cycles
100000 times kmalloc(2048)/kfree -> 67 cycles
100000 times kmalloc(4096)/kfree -> 67 cycles
Kernbench, before:
Average Optimal load -j 12 Run (std deviation):
Elapsed Time 101.873 (1.16069)
User Time 1045.22 (1.60447)
System Time 88.969 (0.559195)
Percent CPU 1112.9 (13.8279)
Context Switches 189140 (2282.15)
Sleeps 99008.6 (768.091)
After:
Average Optimal load -j 12 Run (std deviation):
Elapsed Time 102.47 (0.562732)
User Time 1045.3 (1.34263)
System Time 88.311 (0.342554)
Percent CPU 1105.8 (6.49444)
Context Switches 189081 (2355.78)
Sleeps 99231.5 (800.358)
This patch (of 2):
This commit reorganizes the previous SLAB freelist randomization to
prepare for the SLUB implementation. It moves functions that will be
shared to slab_common.
The entropy functions are changed to align with the SLUB implementation,
now using get_random_(int|long) functions. These functions were chosen
because they provide a bit more entropy early on boot and better
performance when specific arch instructions are not available.
[akpm@linux-foundation.org: fix build]
Link: http://lkml.kernel.org/r/1464295031-26375-2-git-send-email-thgarnie@google.com
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
wait_sb_inodes() currently does a walk of all inodes in the filesystem
to find dirty one to wait on during sync. This is highly inefficient
and wastes a lot of CPU when there are lots of clean cached inodes that
we don't need to wait on.
To avoid this "all inode" walk, we need to track inodes that are
currently under writeback that we need to wait for. We do this by
adding inodes to a writeback list on the sb when the mapping is first
tagged as having pages under writeback. wait_sb_inodes() can then walk
this list of "inodes under IO" and wait specifically just for the inodes
that the current sync(2) needs to wait for.
Define a couple helpers to add/remove an inode from the writeback list
and call them when the overall mapping is tagged for or cleared from
writeback. Update wait_sb_inodes() to walk only the inodes under
writeback due to the sync.
With this change, filesystem sync times are significantly reduced for
fs' with largely populated inode caches and otherwise no other work to
do. For example, on a 16xcpu 2GHz x86-64 server, 10TB XFS filesystem
with a ~10m entry inode cache, sync times are reduced from ~7.3s to less
than 0.1s when the filesystem is fully clean.
Link: http://lkml.kernel.org/r/1466594593-6757-2-git-send-email-bfoster@redhat.com
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Holger Hoffstätte <holger.hoffstaette@applied-asynchrony.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 mm updates from Ingo Molnar:
"Various x86 low level modifications:
- preparatory work to support virtually mapped kernel stacks (Andy
Lutomirski)
- support for 64-bit __get_user() on 32-bit kernels (Benjamin
LaHaise)
- (involved) workaround for Knights Landing CPU erratum (Dave Hansen)
- MPX enhancements (Dave Hansen)
- mremap() extension to allow remapping of the special VDSO vma, for
purposes of user level context save/restore (Dmitry Safonov)
- hweight and entry code cleanups (Borislav Petkov)
- bitops code generation optimizations and cleanups with modern GCC
(H. Peter Anvin)
- syscall entry code optimizations (Paolo Bonzini)"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
x86/mm/cpa: Add missing comment in populate_pdg()
x86/mm/cpa: Fix populate_pgd(): Stop trying to deallocate failed PUDs
x86/syscalls: Add compat_sys_preadv64v2/compat_sys_pwritev64v2
x86/smp: Remove unnecessary initialization of thread_info::cpu
x86/smp: Remove stack_smp_processor_id()
x86/uaccess: Move thread_info::addr_limit to thread_struct
x86/dumpstack: Rename thread_struct::sig_on_uaccess_error to sig_on_uaccess_err
x86/uaccess: Move thread_info::uaccess_err and thread_info::sig_on_uaccess_err to thread_struct
x86/dumpstack: When OOPSing, rewind the stack before do_exit()
x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm
x86/dumpstack/64: Handle faults when printing the "Stack: " part of an OOPS
x86/dumpstack: Try harder to get a call trace on stack overflow
x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables()
x86/mm/cpa: In populate_pgd(), don't set the PGD entry until it's populated
x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()
x86/mm: Use pte_none() to test for empty PTE
x86/mm: Disallow running with 32-bit PTEs to work around erratum
x86/mm: Ignore A/D bits in pte/pmd/pud_none()
x86/mm: Move swap offset/type up in PTE to work around erratum
x86/entry: Inline enter_from_user_mode()
...
The memory controller has quite a bit of state that usually outlives the
cgroup and pins its CSS until said state disappears. At the same time
it imposes a 16-bit limit on the CSS ID space to economically store IDs
in the wild. Consequently, when we use cgroups to contain frequent but
small and short-lived jobs that leave behind some page cache, we quickly
run into the 64k limitations of outstanding CSSs. Creating a new cgroup
fails with -ENOSPC while there are only a few, or even no user-visible
cgroups in existence.
Although pinning CSSs past cgroup removal is common, there are only two
instances that actually need an ID after a cgroup is deleted: cache
shadow entries and swapout records.
Cache shadow entries reference the ID weakly and can deal with the CSS
having disappeared when it's looked up later. They pose no hurdle.
Swap-out records do need to pin the css to hierarchically attribute
swapins after the cgroup has been deleted; though the only pages that
remain swapped out after offlining are tmpfs/shmem pages. And those
references are under the user's control, so they are manageable.
This patch introduces a private 16-bit memcg ID and switches swap and
cache shadow entries over to using that. This ID can then be recycled
after offlining when the CSS remains pinned only by objects that don't
specifically need it.
This script demonstrates the problem by faulting one cache page in a new
cgroup and deleting it again:
set -e
mkdir -p pages
for x in `seq 128000`; do
[ $((x % 1000)) -eq 0 ] && echo $x
mkdir /cgroup/foo
echo $$ >/cgroup/foo/cgroup.procs
echo trex >pages/$x
echo $$ >/cgroup/cgroup.procs
rmdir /cgroup/foo
done
When run on an unpatched kernel, we eventually run out of possible IDs
even though there are no visible cgroups:
[root@ham ~]# ./cssidstress.sh
[...]
65000
mkdir: cannot create directory '/cgroup/foo': No space left on device
After this patch, the IDs get released upon cgroup destruction and the
cache and css objects get released once memory reclaim kicks in.
[hannes@cmpxchg.org: init the IDR]
Link: http://lkml.kernel.org/r/20160621154601.GA22431@cmpxchg.org
Fixes: b2052564e6 ("mm: memcontrol: continue cache reclaim from offlined groups")
Link: http://lkml.kernel.org/r/20160617162516.GD19084@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: John Garcia <john.garcia@mesosphere.io>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Nikolay Borisov <kernel@kyup.com>
Cc: <stable@vger.kernel.org> [3.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 612e44939c ("mm: workingset: eviction buckets for bigmem/lowbit
machines") added a printk without a log level. Quieten it by using
pr_info().
Link: http://lkml.kernel.org/r/1466982072-29836-2-git-send-email-anton@ozlabs.org
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The VM_BUG_ON_PAGE in page_move_anon_rmap() is more trouble than it's
worth: the syzkaller fuzzer hit it again. It's still wrong for some THP
cases, because linear_page_index() was never intended to apply to
addresses before the start of a vma.
That's easily fixed with a signed long cast inside linear_page_index();
and Dmitry has tested such a patch, to verify the false positive. But
why extend linear_page_index() just for this case? when the avoidance in
page_move_anon_rmap() has already grown ugly, and there's no reason for
the check at all (nothing else there is using address or index).
Remove address arg from page_move_anon_rmap(), remove VM_BUG_ON_PAGE,
remove CONFIG_DEBUG_VM PageTransHuge adjustment.
And one more thing: should the compound_head(page) be done inside or
outside page_move_anon_rmap()? It's usually pushed down to the lowest
level nowadays (and mm/memory.c shows no other explicit use of it), so I
think it's better done in page_move_anon_rmap() than by caller.
Fixes: 0798d3c022 ("mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap()")
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1607120444540.12528@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org> [4.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The previous patch addresses the race between split_huge_pmd_address()
and someone changing the pmd. The fix is only for splitting of normal
thp (i.e. pmd-mapped thp,) and for splitting of pte-mapped thp there
still is the similar race.
For splitting pte-mapped thp, the pte's conversion is done by
try_to_unmap_one(TTU_MIGRATION). This function checks
page_check_address() to get the target pte, but it can return NULL under
some race, leading to VM_BUG_ON() in freeze_page(). Fortunately,
page_check_address() already has an argument to decide whether we do a
quick/racy check or not, so let's flip it when called from
freeze_page().
Link: http://lkml.kernel.org/r/1466990929-7452-2-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
early_page_uninitialised looks up an arbitrary PFN. While a machine
without node 0 will boot with "mm, page_alloc: Always return a valid
node from early_pfn_to_nid", it works because it assumes that nodes are
always in PFN order. This is not guaranteed so this patch adds
robustness by always checking if the node being checked is online.
Link: http://lkml.kernel.org/r/1468008031-3848-4-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org> [4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
early_pfn_to_nid can return node 0 if a PFN is invalid on machines that
has no node 0. A machine with only node 1 was observed to crash with
the following message:
BUG: unable to handle kernel paging request at 000000000002a3c8
PGD 0
Modules linked in:
Hardware name: Supermicro H8DSP-8/H8DSP-8, BIOS 080011 06/30/2006
task: ffffffff81c0d500 ti: ffffffff81c00000 task.ti: ffffffff81c00000
RIP: reserve_bootmem_region+0x6a/0xef
CR2: 000000000002a3c8 CR3: 0000000001c06000 CR4: 00000000000006b0
Call Trace:
free_all_bootmem+0x4b/0x12a
mem_init+0x70/0xa3
start_kernel+0x25b/0x49b
The problem is that early_page_uninitialised uses the early_pfn_to_nid
helper which returns node 0 for invalid PFNs. No caller of
early_pfn_to_nid cares except early_page_uninitialised. This patch has
early_pfn_to_nid always return a valid node.
Link: http://lkml.kernel.org/r/1468008031-3848-3-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org> [4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are two bugs on qlist_move_cache(). One is that qlist's tail
isn't set properly. curr->next can be NULL since it is singly linked
list and NULL value on tail is invalid if there is one item on qlist.
Another one is that if cache is matched, qlist_put() is called and it
will set curr->next to NULL. It would cause to stop the loop
prematurely.
These problems come from complicated implementation so I'd like to
re-implement it completely. Implementation in this patch is really
simple. Iterate all qlist_nodes and put them to appropriate list.
Unfortunately, I got this bug sometime ago and lose oops message. But,
the bug looks trivial and no need to attach oops.
Fixes: 55834c5909 ("mm: kasan: initial memory quarantine implementation")
Link: http://lkml.kernel.org/r/1467766348-22419-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Kuthonuzo Luruo <poll.stdin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
madvise_free_huge_pmd should return 0 if the fallback PTE operations are
required. In madvise_free_huge_pmd, if part pages of THP are discarded,
the THP will be split and fallback PTE operations should be used if
splitting succeeds. But the original code will make fallback PTE
operations skipped, after splitting succeeds. Fix that via make
madvise_free_huge_pmd return 0 after splitting successfully, so that the
fallback PTE operations will be done.
Link: http://lkml.kernel.org/r/1467135452-16688-1-git-send-email-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's possible to isolate some freepages in a pageblock and then fail
split_free_page() due to the low watermark check. In this case, we hit
VM_BUG_ON() because the freeing scanner terminated early without a
contended lock or enough freepages.
This should never have been a VM_BUG_ON() since it's not a fatal
condition. It should have been a VM_WARN_ON() at best, or even handled
gracefully.
Regardless, we need to terminate anytime the full pageblock scan was not
done. The logic belongs in isolate_freepages_block(), so handle its
state gracefully by terminating the pageblock loop and making a note to
restart at the same pageblock next time since it was not possible to
complete the scan this time.
[rientjes@google.com: don't rescan pages in a pageblock]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1607111244150.83138@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606291436300.145590@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Minchan Kim <minchan@kernel.org>
Tested-by: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The well-spotted fallocate undo fix is good in most cases, but not when
fallocate failed on the very first page. index 0 then passes lend -1
to shmem_undo_range(), and that has two bad effects: (a) that it will
undo every fallocation throughout the file, unrestricted by the current
range; but more importantly (b) it can cause the undo to hang, because
lend -1 is treated as truncation, which makes it keep on retrying until
every page has gone, but those already fully instantiated will never go
away. Big thank you to xfstests generic/269 which demonstrates this.
Fixes: b9b4bb26af ("tmpfs: don't undo fallocate past its last page")
Cc: stable@vger.kernel.org
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Vladimir Davydov