Both this_cpu_off and cpu_info aren't getting modified post boot, yet
are being accessed on enough code paths that grouping them with other
frequently read items seems desirable. For cpu_info this at the same
time implies removing the cache line alignment (which afaict became
pointless when it got converted to per-CPU data years ago).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/54589BD20200007800044A84@mail.emea.novell.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add "read-mostly" qualifier to the following variables in
smp.h:
- cpu_sibling_map
- cpu_core_map
- cpu_llc_shared_map
- cpu_llc_id
- cpu_number
- x86_cpu_to_apicid
- x86_bios_cpu_apicid
- x86_cpu_to_logical_apicid
As long as all the variables above are only written during the
initialization, this change is meant to prevent the false
sharing. More specifically, on vSMP Foundation platform
x86_cpu_to_apicid shared the same internode_cache_line with
frequently written lapic_events.
From the analysis of the first 33 per_cpu variables out of 219
(memories they describe, to be more specific) the 8 have read_mostly
nature (tlb_vector_offset, cpu_loops_per_jiffy, xen_debug_irq, etc.)
and 25 are frequently written (irq_stack_union, gdt_page,
exception_stacks, idt_desc, etc.).
Assuming that the spread of the rest of the per_cpu variables is
similar, identifying the read mostly memories will make more sense
in terms of long-term code maintenance comparing to identifying
frequently written memories.
Signed-off-by: Vlad Zolotarov <vlad@scalemp.com>
Acked-by: Shai Fultheim <shai@scalemp.com>
Cc: Shai Fultheim (Shai@ScaleMP.com) <Shai@scalemp.com>
Cc: ido@wizery.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1719258.EYKzE4Zbq5@vlad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the embed percpu first chunk allocator, x86 uses either PAGE_SIZE
or PMD_SIZE for atom_size. PMD_SIZE is used when CPU supports PSE so
that percpu areas are aligned to PMD mappings and possibly allow using
PMD mappings in vmalloc areas in the future. Using larger atom_size
doesn't waste actual memory; however, it does require larger vmalloc
space allocation later on for !first chunks.
With reasonably sized vmalloc area, PMD_SIZE shouldn't be a problem
but x86_32 at this point is anything but reasonable in terms of
address space and using larger atom_size reportedly leads to frequent
percpu allocation failures on certain setups.
As there is no reason to not use PMD_SIZE on x86_64 as vmalloc space
is aplenty and most x86_64 configurations support PSE, fix the issue
by always using PMD_SIZE on x86_64 and PAGE_SIZE on x86_32.
v2: drop cpu_has_pse test and make x86_64 always use PMD_SIZE and
x86_32 PAGE_SIZE as suggested by hpa.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yanmin Zhang <yanmin.zhang@intel.com>
Reported-by: ShuoX Liu <shuox.liu@intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <4F97BA98.6010001@intel.com>
Cc: stable@vger.kernel.org
Unlike 64bit, 32bit has been using its own cpu_to_node_map[] for
CPU -> NUMA node mapping. Replace it with early_percpu variable
x86_cpu_to_node_map and share the mapping code with 64bit.
* USE_PERCPU_NUMA_NODE_ID is now enabled for 32bit too.
* x86_cpu_to_node_map and numa_set/clear_node() are moved from
numa_64 to numa. For now, on 32bit, x86_cpu_to_node_map is initialized
with 0 instead of NUMA_NO_NODE. This is to avoid introducing unexpected
behavior change and will be updated once init path is unified.
* srat_detect_node() is now enabled for x86_32 too. It calls
numa_set_node() and initializes the mapping making explicit
cpu_to_node_map[] updates from map/unmap_cpu_to_node() unnecessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: eric.dumazet@gmail.com
Cc: yinghai@kernel.org
Cc: brgerst@gmail.com
Cc: gorcunov@gmail.com
Cc: penberg@kernel.org
Cc: shaohui.zheng@intel.com
Cc: rientjes@google.com
LKML-Reference: <1295789862-25482-15-git-send-email-tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: David Rientjes <rientjes@google.com>
Unlike x86_64, on x86_32, the mapping from cpu to logical apicid
may vary depending on apic in use. cpu_2_logical_apicid[] array
is used for this mapping. Replace it with early percpu variable
x86_cpu_to_logical_apicid to make it better aligned with other
mappings.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: eric.dumazet@gmail.com
Cc: yinghai@kernel.org
Cc: brgerst@gmail.com
Cc: gorcunov@gmail.com
Cc: penberg@kernel.org
Cc: shaohui.zheng@intel.com
Cc: rientjes@google.com
LKML-Reference: <1295789862-25482-5-git-send-email-tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'core-memblock-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (74 commits)
x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S
xen: Cope with unmapped pages when initializing kernel pagetable
memblock, bootmem: Round pfn properly for memory and reserved regions
memblock: Annotate memblock functions with __init_memblock
memblock: Allow memblock_init to be called early
memblock/arm: Fix memblock_region_is_memory() typo
x86, memblock: Remove __memblock_x86_find_in_range_size()
memblock: Fix wraparound in find_region()
x86-32, memblock: Make add_highpages honor early reserved ranges
x86, memblock: Fix crashkernel allocation
arm, memblock: Fix the sparsemem build
memblock: Fix section mismatch warnings
powerpc, memblock: Fix memblock API change fallout
memblock, microblaze: Fix memblock API change fallout
x86: Remove old bootmem code
x86, memblock: Use memblock_memory_size()/memblock_free_memory_size() to get correct dma_reserve
x86: Remove not used early_res code
x86, memblock: Replace e820_/_early string with memblock_
x86: Use memblock to replace early_res
x86, memblock: Use memblock_debug to control debug message print out
...
Fix up trivial conflicts in arch/x86/kernel/setup.c and kernel/Makefile
1. replace find_e820_area with memblock_find_in_range
2. replace reserve_early with memblock_x86_reserve_range
3. replace free_early with memblock_x86_free_range.
4. NO_BOOTMEM will switch to use memblock too.
5. use _e820, _early wrap in the patch, in following patch, will
replace them all
6. because memblock_x86_free_range support partial free, we can remove some special care
7. Need to make sure that memblock_find_in_range() is called after memblock_x86_fill()
so adjust some calling later in setup.c::setup_arch()
-- corruption_check and mptable_update
-v2: Move reserve_brk() early
Before fill_memblock_area, to avoid overlap between brk and memblock_find_in_range()
that could happen We have more then 128 RAM entry in E820 tables, and
memblock_x86_fill() could use memblock_find_in_range() to find a new place for
memblock.memory.region array.
and We don't need to use extend_brk() after fill_memblock_area()
So move reserve_brk() early before fill_memblock_area().
-v3: Move find_smp_config early
To make sure memblock_find_in_range not find wrong place, if BIOS doesn't put mptable
in right place.
-v4: Treat RESERVED_KERN as RAM in memblock.memory. and they are already in
memblock.reserved already..
use __NOT_KEEP_MEMBLOCK to make sure memblock related code could be freed later.
-v5: Generic version __memblock_find_in_range() is going from high to low, and for 32bit
active_region for 32bit does include high pages
need to replace the limit with memblock.default_alloc_limit, aka get_max_mapped()
-v6: Use current_limit instead
-v7: check with MEMBLOCK_ERROR instead of -1ULL or -1L
-v8: Set memblock_can_resize early to handle EFI with more RAM entries
-v9: update after kmemleak changes in mainline
Suggested-by: David S. Miller <davem@davemloft.net>
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
boot_cpu_id is there for historical reasons and was renamed to
boot_cpu_physical_apicid in patch:
c70dcb7 x86: change boot_cpu_id to boot_cpu_physical_apicid
However, there are some remaining occurrences of boot_cpu_id that are
never touched in the kernel and thus its value is always 0.
This patch removes boot_cpu_id completely.
Signed-off-by: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1279731838-1522-8-git-send-email-robert.richter@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pointed out by Lucas who found the new one in a comment in
setup_percpu.c. And then I fixed the others that I grepped
for.
Reported-by: Lucas <canolucas@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit e534c7c5f8 ("numa: x86_64: use generic percpu var
numa_node_id() implementation") broke numa systems that don't have ram
on node0 when MEMORY_HOTPLUG is enabled, because cpu_up() will call
cpu_to_node() before per_cpu(numa_node) is setup for APs.
When Node0 doesn't have RAM, on x86, cpus already round it to nearest
node with RAM in x86_cpu_to_node_map. and per_cpu(numa_node) is not set
up until in c_init for APs.
When later cpu_up() calling cpu_to_node() will get 0 again, and make it
online even there is no RAM on node0. so later all APs can not booted up,
and later will have panic.
[ 1.611101] On node 0 totalpages: 0
.........
[ 2.608558] On node 0 totalpages: 0
[ 2.612065] Brought up 1 CPUs
[ 2.615199] Total of 1 processors activated (3990.31 BogoMIPS).
...
93.225341] calling loop_init+0x0/0x1a4 @ 1
[ 93.229314] PERCPU: allocation failed, size=80 align=8, failed to populate
[ 93.246539] Pid: 1, comm: swapper Tainted: G W 2.6.35-rc4-tip-yh-04371-gd64e6c4-dirty #354
[ 93.264621] Call Trace:
[ 93.266533] [<ffffffff81125e43>] pcpu_alloc+0x83a/0x8e7
[ 93.270710] [<ffffffff81125f15>] __alloc_percpu+0x10/0x12
[ 93.285849] [<ffffffff8140786c>] alloc_disk_node+0x94/0x16d
[ 93.291811] [<ffffffff81407956>] alloc_disk+0x11/0x13
[ 93.306157] [<ffffffff81503e51>] loop_alloc+0xa7/0x180
[ 93.310538] [<ffffffff8277ef48>] loop_init+0x9b/0x1a4
[ 93.324909] [<ffffffff8277eead>] ? loop_init+0x0/0x1a4
[ 93.329650] [<ffffffff810001f2>] do_one_initcall+0x57/0x136
[ 93.345197] [<ffffffff827486d0>] kernel_init+0x184/0x20e
[ 93.348146] [<ffffffff81034954>] kernel_thread_helper+0x4/0x10
[ 93.365194] [<ffffffff81c7cc3c>] ? restore_args+0x0/0x30
[ 93.369305] [<ffffffff8274854c>] ? kernel_init+0x0/0x20e
[ 93.386011] [<ffffffff81034950>] ? kernel_thread_helper+0x0/0x10
[ 93.392047] loop: out of memory
...
Try to assign per_cpu(numa_node) early
[akpm@linux-foundation.org: tidy up code comment]
Signed-off-by: Yinghai <yinghai@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, smpboot: Fix cores per node printing on boot
x86/amd-iommu: Fall back to GART if initialization fails
x86/amd-iommu: Fix crash when request_mem_region fails
x86/mm: Remove unused DBG() macro
arch/x86/kernel: Add missing spin_unlock
* 'for-35' of git://repo.or.cz/linux-kbuild: (81 commits)
kbuild: Revert part of e8d400a to resolve a conflict
kbuild: Fix checking of scm-identifier variable
gconfig: add support to show hidden options that have prompts
menuconfig: add support to show hidden options which have prompts
gconfig: remove show_debug option
gconfig: remove dbg_print_ptype() and dbg_print_stype()
kconfig: fix zconfdump()
kconfig: some small fixes
add random binaries to .gitignore
kbuild: Include gen_initramfs_list.sh and the file list in the .d file
kconfig: recalc symbol value before showing search results
.gitignore: ignore *.lzo files
headerdep: perlcritic warning
scripts/Makefile.lib: Align the output of LZO
kbuild: Generate modules.builtin in make modules_install
Revert "kbuild: specify absolute paths for cscope"
kbuild: Do not unnecessarily regenerate modules.builtin
headers_install: use local file handles
headers_check: fix perl warnings
export_report: fix perl warnings
...
x86 arch specific changes to use generic numa_node_id() based on generic
percpu variable infrastructure. Back out x86's custom version of
numa_node_id()
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Embedding percpu first chunk allocator can now handle very sparse unit
mapping. Use embedding allocator instead of lpage for 64bit NUMA.
This removes extra TLB pressure and the need to do complex and fragile
dancing when changing page attributes.
For 32bit, using very sparse unit mapping isn't a good idea because
the vmalloc space is very constrained. 32bit NUMA machines aren't
exactly the focus of optimization and it isn't very clear whether
lpage performs better than page. Use page first chunk allocator for
32bit NUMAs.
As this leaves setup_pcpu_*() functions pretty much empty, fold them
into setup_per_cpu_areas().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <andi@firstfloor.org>
Now that percpu core can handle very sparse units, given that vmalloc
space is large enough, embedding first chunk allocator can use any
memory to build the first chunk. This patch teaches
pcpu_embed_first_chunk() about distances between cpus and to use
alloc/free callbacks to allocate node specific areas for each group
and use them for the first chunk.
This brings the benefits of embedding allocator to NUMA configurations
- no extra TLB pressure with the flexibility of unified dynamic
allocator and no need to restructure arch code to build memory layout
suitable for percpu. With units put into atom_size aligned groups
according to cpu distances, using large page for dynamic chunks is
also easily possible with falling back to reuglar pages if large
allocation fails.
Embedding allocator users are converted to specify NULL
cpu_distance_fn, so this patch doesn't cause any visible behavior
difference. Following patches will convert them.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently units are mapped sequentially into address space. This
patch adds pcpu_unit_offsets[] which allows units to be mapped to
arbitrary offsets from the chunk base address. This is necessary to
allow sparse embedding which might would need to allocate address
ranges and memory areas which aren't aligned to unit size but
allocation atom size (page or large page size). This also simplifies
things a bit by removing the need to calculate offset from unit
number.
With this change, there's no need for the arch code to know
pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk
allocators to return regular 0 or -errno return code instead of unit
size or -errno.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Till now, non-linear cpu->unit map was expressed using an integer
array which maps each cpu to a unit and used only by lpage allocator.
Although how many units have been placed in a single contiguos area
(group) is known while building unit_map, the information is lost when
the result is recorded into the unit_map array. For lpage allocator,
as all allocations are done by lpages and whether two adjacent lpages
are in the same group or not is irrelevant, this didn't cause any
problem. Non-linear cpu->unit mapping will be used for sparse
embedding and this grouping information is necessary for that.
This patch introduces pcpu_alloc_info which contains all the
information necessary for initializing percpu allocator.
pcpu_alloc_info contains array of pcpu_group_info which describes how
units are grouped and mapped to cpus. pcpu_group_info also has
base_offset field to specify its offset from the chunk's base address.
pcpu_build_alloc_info() initializes this field as if all groups are
allocated back-to-back as is currently done but this will be used to
sparsely place groups.
pcpu_alloc_info is a rather complex data structure which contains a
flexible array which in turn points to nested cpu_map arrays.
* pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to
help dealing with pcpu_alloc_info.
* pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info,
generalized and renamed to pcpu_build_alloc_info().
@cpu_distance_fn may be NULL indicating that all cpus are of
LOCAL_DISTANCE.
* pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info,
generalized and renamed to pcpu_dump_alloc_info(). It now also
prints which group each alloc unit belongs to.
* pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the
separate parameters. All first chunk allocators are updated to use
pcpu_build_alloc_info() to build alloc_info and call
pcpu_setup_first_chunk() with it. This has the side effect of
packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are
possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4.
* x86 setup_pcpu_lpage() is updated to deal with alloc_info.
* sparc64 setup_per_cpu_areas() is updated to build alloc_info.
Although the changes made by this patch are pretty pervasive, it
doesn't cause any behavior difference other than packing of sparse
cpus. It mostly changes how information is passed among
initialization functions and makes room for more flexibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
First chunk allocators assume percpu areas have been linked using one
of PERCPU_*() macros and depend on __per_cpu_load symbol defined by
those macros, so there isn't much point in passing in static area size
explicitly when it can be easily calculated from __per_cpu_start and
__per_cpu_end. Drop @static_size from all percpu first chunk
allocators and helpers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that all first chunk allocators are in mm/percpu.c, it makes sense
to make generalize percpu_alloc kernel parameter. Define PCPU_FC_*
and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code
can use the set value to determine which first chunk allocator to use.
Signed-off-by: Tejun Heo <tj@kernel.org>
Page size isn't always 4k depending on arch and configuration. Rename
4k first chunk allocator to page.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Conflicts:
arch/sparc/kernel/smp_64.c
arch/x86/kernel/cpu/perf_counter.c
arch/x86/kernel/setup_percpu.c
drivers/cpufreq/cpufreq_ondemand.c
mm/percpu.c
Conflicts in core and arch percpu codes are mostly from commit
ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many
num_possible_cpus() with nr_cpu_ids. As for-next branch has moved all
the first chunk allocators into mm/percpu.c, the changes are moved
from arch code to mm/percpu.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu code has been assuming num_possible_cpus() == nr_cpu_ids which
is incorrect if cpu_possible_map contains holes. This causes percpu
code to access beyond allocated memories and vmalloc areas. On a
sparc64 machine with cpus 0 and 2 (u60), this triggers the following
warning or fails boot.
WARNING: at /devel/tj/os/work/mm/vmalloc.c:106 vmap_page_range_noflush+0x1f0/0x240()
Modules linked in:
Call Trace:
[00000000004b17d0] vmap_page_range_noflush+0x1f0/0x240
[00000000004b1840] map_vm_area+0x20/0x60
[00000000004b1950] __vmalloc_area_node+0xd0/0x160
[0000000000593434] deflate_init+0x14/0xe0
[0000000000583b94] __crypto_alloc_tfm+0xd4/0x1e0
[00000000005844f0] crypto_alloc_base+0x50/0xa0
[000000000058b898] alg_test_comp+0x18/0x80
[000000000058dad4] alg_test+0x54/0x180
[000000000058af00] cryptomgr_test+0x40/0x60
[0000000000473098] kthread+0x58/0x80
[000000000042b590] kernel_thread+0x30/0x60
[0000000000472fd0] kthreadd+0xf0/0x160
---[ end trace 429b268a213317ba ]---
This patch fixes generic percpu functions and sparc64
setup_per_cpu_areas() so that they handle sparse cpu_possible_map
properly.
Please note that on x86, cpu_possible_map() doesn't contain holes and
thus num_possible_cpus() == nr_cpu_ids and this patch doesn't cause
any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Large page first chunk allocator is primarily used for NUMA machines;
however, its NUMA handling is extremely simplistic. Regardless of
their proximity, each cpu is put into separate large page just to
return most of the allocated space back wasting large amount of
vmalloc space and increasing cache footprint.
This patch teachs NUMA details to large page allocator. Given
processor proximity information, pcpu_lpage_build_unit_map() will find
fitting cpu -> unit mapping in which cpus in LOCAL_DISTANCE share the
same large page and not too much virtual address space is wasted.
This greatly reduces the unit and thus chunk size and wastes much less
address space for the first chunk. For example, on 4/4 NUMA machine,
the original code occupied 16MB of virtual space for the first chunk
while the new code only uses 4MB - one 2MB page for each node.
[ Impact: much better space efficiency on NUMA machines ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Miller <davem@davemloft.net>
Generalize and move x86 setup_pcpu_lpage() into
pcpu_lpage_first_chunk(). setup_pcpu_lpage() now is a simple wrapper
around the generalized version. Other than taking size parameters and
using arch supplied callbacks to allocate/free/map memory,
pcpu_lpage_first_chunk() is identical to the original implementation.
This simplifies arch code and will help converting more archs to
dynamic percpu allocator.
While at it, factor out pcpu_calc_fc_sizes() which is common to
pcpu_embed_first_chunk() and pcpu_lpage_first_chunk().
[ Impact: code reorganization and generalization ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk().
setup_pcpu_4k() now is a simple wrapper around the generalized
version. Other than taking size parameters and using arch supplied
callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical
to the original implementation.
This simplifies arch code and will help converting more archs to
dynamic percpu allocator.
While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for
consistency.
[ Impact: code reorganization and generalization ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
The only extra feature @unit_size provides is making dead space at the
end of the first chunk which doesn't have any valid usecase. Drop the
parameter. This will increase consistency with generalized 4k
allocator.
James Bottomley spotted missing conversion for the default
setup_per_cpu_areas() which caused build breakage on all arcsh which
use it.
[ Impact: drop unused code path ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Ingo Molnar <mingo@elte.hu>
On extreme configuration (e.g. 32bit 32-way NUMA machine), lpage
percpu first chunk allocator can consume too much of vmalloc space.
Make it fall back to 4k allocator if the consumption goes over 20%.
[ Impact: add sanity check for lpage percpu first chunk allocator ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
According to Andi, it isn't clear whether lpage allocator is worth the
trouble as there are many processors where PMD TLB is far scarcer than
PTE TLB. The advantage or disadvantage probably depends on the actual
size of percpu area and specific processor. As performance
degradation due to TLB pressure tends to be highly workload specific
and subtle, it is difficult to decide which way to go without more
data.
This patch implements percpu_alloc kernel parameter to allow selecting
which first chunk allocator to use to ease debugging and testing.
While at it, make sure all the failure paths report why something
failed to help determining why certain allocator isn't working. Also,
kill the "Great future plan" comment which had already been realized
quite some time ago.
[ Impact: allow explicit percpu first chunk allocator selection ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
lpage allocator aliases a PMD page for each cpu and returns whatever
is unused to the page allocator. When the pageattr of the recycled
pages are changed, this makes the two aliases point to the overlapping
regions with different attributes which isn't allowed and known to
cause subtle data corruption in certain cases.
This can be handled in simliar manner to the x86_64 highmap alias.
pageattr code should detect if the target pages have PMD alias and
split the PMD alias and synchronize the attributes.
pcpur allocator is updated to keep the allocated PMD pages map sorted
in ascending address order and provide pcpu_lpage_remapped() function
which binary searches the array to determine whether the given address
is aliased and if so to which address. pageattr is updated to use
pcpu_lpage_remapped() to detect the PMD alias and split it up as
necessary from cpa_process_alias().
Jan Beulich spotted the original problem and incorrect usage of vaddr
instead of laddr for lookup.
With this, lpage percpu allocator should work correctly. Re-enable
it.
[ Impact: fix subtle lpage pageattr bug and re-enable lpage ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Make the following changes in preparation of coming pageattr updates.
* Define and use array of struct pcpul_ent instead of array of
pointers. The only difference is ->cpu field which is set but
unused yet.
* Rename variables according to the above change.
* Rename local variable vm to pcpul_vm and move it out of the
function.
[ Impact: no functional difference ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
The "remap" allocator remaps large pages to build the first chunk;
however, the name isn't very good because 4k allocator remaps too and
the whole point of the remap allocator is using large page mapping.
The allocator will be generalized and exported outside of x86, rename
it to lpage before that happens.
percpu_alloc kernel parameter is updated to accept both "remap" and
"lpage" for lpage allocator.
[ Impact: code cleanup, kernel parameter argument updated ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
In the failure path, setup_pcpu_remap() tries to free the area which
has already been freed to make holes in the large page. Fix it.
[ Impact: fix duplicate free in failure path ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (22 commits)
x86: fix system without memory on node0
x86, mm: Fix node_possible_map logic
mm, x86: remove MEMORY_HOTPLUG_RESERVE related code
x86: make sparse mem work in non-NUMA mode
x86: process.c, remove useless headers
x86: merge process.c a bit
x86: use sparse_memory_present_with_active_regions() on UMA
x86: unify 64-bit UMA and NUMA paging_init()
x86: Allow 1MB of slack between the e820 map and SRAT, not 4GB
x86: Sanity check the e820 against the SRAT table using e820 map only
x86: clean up and and print out initial max_pfn_mapped
x86/pci: remove rounding quirk from e820_setup_gap()
x86, e820, pci: reserve extra free space near end of RAM
x86: fix typo in address space documentation
x86: 46 bit physical address support on 64 bits
x86, mm: fault.c, use printk_once() in is_errata93()
x86: move per-cpu mmu_gathers to mm/init.c
x86: move max_pfn_mapped and max_low_pfn_mapped to setup.c
x86: unify noexec handling
x86: remove (null) in /sys kernel_page_tables
...
Remap percpu allocator has subtle bug when combined with page
attribute changing. Remap percpu allocator aliases PMD pages for the
first chunk and as pageattr doesn't know about the alias it ends up
updating page attributes of the original mapping thus leaving the
alises in inconsistent state which might lead to subtle data
corruption. Please read the following threads for more information:
http://thread.gmane.org/gmane.linux.kernel/835783
The following is the proposed fix which teaches pageattr about percpu
aliases.
http://thread.gmane.org/gmane.linux.kernel/837157
However, the above changes are deemed too pervasive for upstream
inclusion for 2.6.30 release, so this patch essentially disables
the remap allocator for the time being.
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4A1A0A27.4050301@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Jack found a boot crash on a system which doesn't have memory on node0.
It turns out with recent per_cpu changes, node_number for BSP will always
be 0, and it is not consistent to cpu_to_node() that might set it to a
different (nearer) node already.
aka when numa_set_node() for node0 is called early before per_cpu area is
setup:
two places touched that per_cpu(node_number,):
1. in cpu/common.c::cpu_init() and it is not for BP
| #ifdef CONFIG_NUMA
| if (cpu != 0 && percpu_read(node_number) == 0 &&
| cpu_to_node(cpu) != NUMA_NO_NODE)
| percpu_write(node_number, cpu_to_node(cpu));
| #endif
for BP: traps_init ==> cpu_init
for AP: start_secondary ==> cpu_init
2. cpu/intel.c or amd.c::srat_detect_node via numa_set_node()
for BP: check_bugs ==> identify_boot_cpu ==> identify_cpu()
that is rather later before numa_node_id() is used for BP...
for AP: start_secondary => smp_callin => smp_store_cpu_info() =>
=> identify_secondary_cpu => identify_cpu()
so try to set that for BP earlier in setup_per_cpu_areas(), and
don't bother to set that for APs there (it will be updated later
and will be used later)
(and don't mess the 0 before the copying BP per_cpu data to APs)
[ Impact: fix boot crash on memoryless node-0 ]
Reported-and-tested-by: Jack Steiner <steiner@sgi.com>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4A0C4A02.7050401@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
those code pcpu_need_numa(), should be removed.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David Miller <davem@davemloft.net>
LKML-Reference: <49D31770.9090502@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
setup_percpu_remap() is for NUMA machines yet it bailed out with
-EINVAL if pcpu_need_numa(). Fix the inverted condition.
This problem was reported by David Miller and verified by Yinhai Lu.
Reported-by: David Miller <davem@davemloft.net>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <49D30469.8020006@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: code reorganization
Separate out embedding first chunk setup helper from x86 embedding
first chunk allocator and put it in mm/percpu.c. This will be used by
the default percpu first chunk allocator and possibly by other archs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: cleanup, more flexibility for first chunk init
Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto.
This restriction stemmed from implementation detail and made things a
bit less intuitive. This patch allows @dyn_size to be specified
regardless of @unit_size and swaps the positions of @dyn_size and
@unit_size so that the parameter order makes more sense (static,
reserved and dyn sizes followed by enclosing unit_size).
While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check.
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: fix relocation overflow during module load
x86_64 uses 32bit relocations for symbol access and static percpu
symbols whether in core or modules must be inside 2GB of the percpu
segement base which the dynamic percpu allocator doesn't guarantee.
This patch makes x86_64 reserve PERCPU_MODULE_RESERVE bytes in the
first chunk so that module percpu areas are always allocated from the
first chunk which is always inside the relocatable range.
This problem exists for any percpu allocator but is easily triggered
when using the embedding allocator because the second chunk is located
beyond 2GB on it.
This patch also changes the meaning of PERCPU_DYNAMIC_RESERVE such
that it only indicates the size of the area to reserve for dynamic
allocation as static and dynamic areas can be separate. New
PERCPU_DYNAMIC_RESERVED is increased by 4k for both 32 and 64bits as
the reserved area separation eats away some allocatable space and
having slightly more headroom (currently between 4 and 8k after
minimal boot sans module area) makes sense for common case
performance.
x86_32 can address anywhere from anywhere and doesn't need reserving.
Mike Galbraith first reported the problem first and bisected it to the
embedding percpu allocator commit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Mike Galbraith <efault@gmx.de>
Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Impact: add reserved allocation functionality and use it for module
percpu variables
This patch implements reserved allocation from the first chunk. When
setting up the first chunk, arch can ask to set aside certain number
of bytes right after the core static area which is available only
through a separate reserved allocator. This will be used primarily
for module static percpu variables on architectures with limited
relocation range to ensure that the module perpcu symbols are inside
the relocatable range.
If reserved area is requested, the first chunk becomes reserved and
isn't available for regular allocation. If the first chunk also
includes piggy-back dynamic allocation area, a separate chunk mapping
the same region is created to serve dynamic allocation. The first one
is called static first chunk and the second dynamic first chunk.
Although they share the page map, their different area map
initializations guarantee they serve disjoint areas according to their
purposes.
If arch doesn't setup reserved area, reserved allocation is handled
like any other allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: reduce unnecessary memory usage on certain configurations
Embedding percpu allocator allocates unit_size *
smp_num_possible_cpus() bytes consecutively and use it for the first
chunk. However, if the static area is small, this can result in
excessive prellocated free space in the first chunk due to
PCPU_MIN_UNIT_SIZE restriction.
This patch makes embedding percpu allocator preallocate only what's
necessary as described by PERPCU_DYNAMIC_RESERVE and return the
leftover to the bootmem allocator.
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: argument semantic cleanup
In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant
auto-sizing. It's okay for @unit_size as 0 doesn't make sense but 0
dynamic reserve size is valid. Alos, if arch @dyn_size is calculated
from other parameters, it might end up passing in 0 @dyn_size and
malfunction when the size is automatically adjusted.
This patch makes both @unit_size and @dyn_size ssize_t and use -1 for
auto sizing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Recent changes in setup_percpu.c made a now meaningless DBG()
statement fail to compile and introduced a
comparison-of-different-types warning. Fix them.
Compile failure is reported by Ingo Molnar.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Impact: add better first percpu allocation for NUMA
On NUMA, embedding allocator can't be used as different units can't be
made to fall in the correct NUMA nodes. To use large page mapping,
each unit needs to be remapped. However, percpu areas are usually
much smaller than large page size and unused space hurts a lot as the
number of cpus grow. This allocator remaps large pages for each chunk
but gives back unused part to the bootmem allocator making the large
pages mapped twice.
This adds slightly to the TLB pressure but is much better than using
4k mappings while still being NUMA-friendly.
Ingo suggested that this would be the correct approach for NUMA.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Jan Beulich