It is not sufficient to only implement get_user_pages_fast(), you
must also implement the atomic version __get_user_pages_fast()
otherwise you end up using the weak symbol fallback implementation
which simply returns zero.
This is dangerous, because it causes the futex code to loop forever
if transparent hugepages are supported (see get_futex_key()).
Signed-off-by: David S. Miller <davem@davemloft.net>
The large PMD path needs to check _PAGE_VALID not _PAGE_PRESENT, to
decide if it needs to bail and return 0.
pmd_large() should therefore just check _PAGE_PMD_HUGE.
Calls to gup_huge_pmd() are guarded with a check of pmd_large(), so we
just need to add a valid bit check.
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that we have 64-bits for PMDs we can stop using special encodings
for the huge PMD values, and just put real PTEs in there.
We allocate a _PAGE_PMD_HUGE bit to distinguish between plain PMDs and
huge ones. It is the same for both 4U and 4V PTE layouts.
We also use _PAGE_SPECIAL to indicate the splitting state, since a
huge PMD cannot also be special.
All of the PMD --> PTE translation code disappears, and most of the
huge PMD bit modifications and tests just degenerate into the PTE
operations. In particular USER_PGTABLE_CHECK_PMD_HUGE becomes
trivial.
As a side effect, normal PMDs don't shift the physical address around.
This also speeds up the page table walks in the TLB miss paths since
they don't have to do the shifts any more.
Another non-trivial aspect is that pte_modify() has to be changed
to preserve the _PAGE_PMD_HUGE bits as well as the page size field
of the pte.
Signed-off-by: David S. Miller <davem@davemloft.net>
Mostly mirrors the s390 logic, as unlike x86 we don't need the
SetPageReferenced() bits.
On sparc64 we also lack a user/privileged bit in the huge PMDs.
In order to make this work for THP and non-THP builds, some header
file adjustments were necessary. Namely, provide the PMD_HUGE_* bit
defines and the pmd_large() inline unconditionally rather than
protected by TRANSPARENT_HUGEPAGE.
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This avoids duplicating the function in every arch gup_fast.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Up to this point the code assumed old refcounting for hugepages (pre-thp).
This updates the code directly to the thp mapcount tail page refcounting.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David S. Miller