I don't know of any problem from the way it's used in our current tree,
but there is one defect in page migration's custom put_new_page feature.

An unused newpage is expected to be released with the put_new_page(), but
there was one MIGRATEPAGE_SUCCESS (0) path which released it with
putback_lru_page(): which can be very wrong for a custom pool.

Fixed more easily by resetting put_new_page once it won't be needed, than
by adding a further flag to modify the rc test.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It's migrate.c not migration,c, and nowadays putback_movable_pages() not
putback_lru_pages().
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: NRafael Aquini <aquini@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After v4.3's commit 0610c25d ("memcg: fix dirty page migration")
mem_cgroup_migrate() doesn't have much to offer in page migration: convert
migrate_misplaced_transhuge_page() to set_page_memcg() instead.

Then rename mem_cgroup_migrate() to mem_cgroup_replace_page(), since its
remaining callers are replace_page_cache_page() and shmem_replace_page():
both of whom passed lrucare true, so just eliminate that argument.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit e6c509f8 ("mm: use clear_page_mlock() in page_remove_rmap()")
in v3.7 inadvertently made mlock_migrate_page() impotent: page migration
unmaps the page from userspace before migrating, and that commit clears
PageMlocked on the final unmap, leaving mlock_migrate_page() with
nothing to do.  Not a serious bug, the next attempt at reclaiming the
page would fix it up; but a betrayal of page migration's intent - the
new page ought to emerge as PageMlocked.

I don't see how to fix it for mlock_migrate_page() itself; but easily
fixed in remove_migration_pte(), by calling mlock_vma_page() when the vma
is VM_LOCKED - under pte lock as in try_to_unmap_one().

Delete mlock_migrate_page()?  Not quite, it does still serve a purpose for
migrate_misplaced_transhuge_page(): where we could replace it by a test,
clear_page_mlock(), mlock_vma_page() sequence; but would that be an
improvement?  mlock_migrate_page() is fairly lean, and let's make it
leaner by skipping the irq save/restore now clearly not needed.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

KernelThreadSanitizer (ktsan) has shown that the down_read_trylock() of
mmap_sem in try_to_unmap_one() (when going to set PageMlocked on a page
found mapped in a VM_LOCKED vma) is ineffective against races with
exit_mmap()'s munlock_vma_pages_all(), because mmap_sem is not held when
tearing down an mm.

But that's okay, those races are benign; and although we've believed for
years in that ugly down_read_trylock(), it's unsuitable for the job, and
frustrates the good intention of setting PageMlocked when it fails.

It just doesn't matter if here we read vm_flags an instant before or after
a racing mlock() or munlock() or exit_mmap() sets or clears VM_LOCKED: the
syscalls (or exit) work their way up the address space (taking pt locks
after updating vm_flags) to establish the final state.

We do still need to be careful never to mark a page Mlocked (hence
unevictable) by any race that will not be corrected shortly after.  The
page lock protects from many of the races, but not all (a page is not
necessarily locked when it's unmapped).  But the pte lock we just dropped
is good to cover the rest (and serializes even with
munlock_vma_pages_all(), so no special barriers required): now hold on to
the pte lock while calling mlock_vma_page().  Is that lock ordering safe?
Yes, that's how follow_page_pte() calls it, and how page_remove_rmap()
calls the complementary clear_page_mlock().

This fixes the following case (though not a case which anyone has
complained of), which mmap_sem did not: truncation's preliminary
unmap_mapping_range() is supposed to remove even the anonymous COWs of
filecache pages, and that might race with try_to_unmap_one() on a
VM_LOCKED vma, so that mlock_vma_page() sets PageMlocked just after
zap_pte_range() unmaps the page, causing "Bad page state (mlocked)" when
freed.  The pte lock protects against this.

You could say that it also protects against the more ordinary case, racing
with the preliminary unmapping of a filecache page itself: but in our
current tree, that's independently protected by i_mmap_rwsem; and that
race would be why "Bad page state (mlocked)" was seen before commit
48ec833b ("Revert mm/memory.c: share the i_mmap_rwsem").

Vlastimil Babka points out another race which this patch protects against.
 try_to_unmap_one() might reach its mlock_vma_page() TestSetPageMlocked a
moment after munlock_vma_pages_all() did its Phase 1 TestClearPageMlocked:
leaving PageMlocked and unevictable when it should be evictable.  mmap_sem
is ineffective because exit_mmap() does not hold it; page lock ineffective
because __munlock_pagevec() only takes it afterwards, in Phase 2; pte lock
is effective because __munlock_pagevec_fill() takes it to get the page,
after VM_LOCKED was cleared from vm_flags, so visible to try_to_unmap_one.

Kirill Shutemov points out that if the compiler chooses to implement a
"vma->vm_flags &= VM_WHATEVER" or "vma->vm_flags |= VM_WHATEVER" operation
with an intermediate store of unrelated bits set, since I'm here foregoing
its usual protection by mmap_sem, try_to_unmap_one() might catch sight of
a spurious VM_LOCKED in vm_flags, and make the wrong decision.  This does
not appear to be an immediate problem, but we may want to define vm_flags
accessors in future, to guard against such a possibility.

While we're here, make a related optimization in try_to_munmap_one(): if
it's doing TTU_MUNLOCK, then there's no point at all in descending the
page tables and getting the pt lock, unless the vma is VM_LOCKED.  Yes,
that can change racily, but it can change racily even without the
optimization: it's not critical.  Far better not to waste time here.

Stopped short of separating try_to_munlock_one() from try_to_munmap_one()
on this occasion, but that's probably the sensible next step - with a
rename, given that try_to_munlock()'s business is to try to set Mlocked.

Updated the unevictable-lru Documentation, to remove its reference to mmap
semaphore, but found a few more updates needed in just that area.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While updating some mm Documentation, I came across a few straggling
references to the non-linear vmas which were happily removed in v4.0.
Delete them.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If ALLOC_SPLIT_PTLOCKS is defined, ptlock_init may fail, in which case we
shouldn't increment NR_PAGETABLE.

Since small allocations, such as ptlock, normally do not fail (currently
they can fail if kmemcg is used though), this patch does not really fix
anything and should be considered as a code cleanup.
Signed-off-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Don't build clear_soft_dirty_pmd() if transparent huge pages are not
enabled.
Signed-off-by: NLaurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As mentioned in the commit 56eecdb9 ("mm: Use ptep/pmdp_set_numa()
for updating _PAGE_NUMA bit"), architectures like ppc64 don't do tlb
flush in set_pte/pmd functions.

So when dealing with existing pte in clear_soft_dirty, the pte must be
cleared before being modified.
Signed-off-by: NLaurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

get_mergeable_page() can only return NULL (also in case of errors) or the
pinned mergeable page.  It can't return an error different than NULL.
This optimizes away the unnecessary error check.

Add a return after the "out:" label in the callee to make it more
readable.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Doing the VM_MERGEABLE check after the page == kpage check won't provide
any meaningful benefit.  The !vma->anon_vma check of find_mergeable_vma is
the only superfluous bit in using find_mergeable_vma because the !PageAnon
check of try_to_merge_one_page() implicitly checks for that, but it still
looks cleaner to share the same find_mergeable_vma().
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This just uses the helper function to cleanup the assumption on the
hlist_node internals.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The stable_nodes can become stale at any time if the underlying pages gets
freed.  The stable_node gets collected and removed from the stable rbtree
if that is detected during the rbtree lookups.

Don't fail the lookup if running into stale stable_nodes, just restart the
lookup after collecting the stale stable_nodes.  Otherwise the CPU spent
in the preparation stage is wasted and the lookup must be repeated at the
next loop potentially failing a second time in a second stale stable_node.

If we don't prune aggressively we delay the merging of the unstable node
candidates and at the same time we delay the freeing of the stale
stable_nodes.  Keeping stale stable_nodes around wastes memory and it
can't provide any benefit.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While at it add it to the file and anon walks too.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Acked-by: NDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Before the previous patch ("memcg: unify slab and other kmem pages
charging"), __mem_cgroup_from_kmem had to handle two types of kmem - slab
pages and pages allocated with alloc_kmem_pages - memcg in the page
struct.  Now we can unify it.  Since after it, this function becomes tiny
we can fold it into mem_cgroup_from_kmem.

[hughd@google.com: move mem_cgroup_from_kmem into list_lru.c]
Signed-off-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and
uncharging kmem pages to memcg, but currently they are not used for
charging slab pages (i.e.  they are only used for charging pages allocated
with alloc_kmem_pages).  The only reason why the slab subsystem uses
special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it
needs to charge to the memcg of kmem cache while memcg_charge_kmem charges
to the memcg that the current task belongs to.

To remove this diversity, this patch adds an extra argument to
__memcg_kmem_charge that can be a pointer to a memcg or NULL.  If it is
not NULL, the function tries to charge to the memcg it points to,
otherwise it charge to the current context.  Next, it makes the slab
subsystem use this function to charge slab pages.

Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only
in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined.  Since
__memcg_kmem_charge stores a pointer to the memcg in the page struct, we
don't need memcg_uncharge_slab anymore and can use free_kmem_pages.
Besides, one can now detect which memcg a slab page belongs to by reading
/proc/kpagecgroup.

Note, this patch switches slab to charge-after-alloc design.  Since this
design is already used for all other memcg charges, it should not make any
difference.

[hannes@cmpxchg.org: better to have an outer function than a magic parameter for the memcg lookup]
Signed-off-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Charging kmem pages proceeds in two steps.  First, we try to charge the
allocation size to the memcg the current task belongs to, then we allocate
a page and "commit" the charge storing the pointer to the memcg in the
page struct.

Such a design looks overcomplicated, because there is not much sense in
trying charging the allocation before actually allocating a page: we won't
be able to consume much memory over the limit even if we charge after
doing the actual allocation, besides we already charge user pages post
factum, so being pedantic with kmem pages just looks pointless.

So this patch simplifies the design by merging the "charge" and the
"commit" steps into the same function, which takes the allocated page.

Also, rename the charge and uncharge methods to memcg_kmem_charge and
memcg_kmem_uncharge and make the charge method return error code instead
of bool to conform to mem_cgroup_try_charge.
Signed-off-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If kernelcore was not specified, or the kernelcore size is zero
(required_movablecore >= totalpages), or the kernelcore size is larger
than totalpages, there is no ZONE_MOVABLE.  We should fill the zone with
both kernel memory and movable memory.
Signed-off-by: NXishi Qiu <qiuxishi@huawei.com>
Reviewed-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: <zhongjiang@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This function incurs in very hot paths and merely does a few loads for
validity check.  Lets inline it, such that we can save the function call
overhead.

(akpm: this is cosmetic - the compiler already inlines vmacache_valid_mm())
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change HIGHMEM_ZONE to be the same as the DMA_ZONE macro.
Signed-off-by: Nyalin wang <yalin.wang2010@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Srinivas Kandagatla reported bad page messages when trying to remove the
bottom 2MB on an ARM based IFC6410 board

  BUG: Bad page state in process swapper  pfn:fffa8
  page:ef7fb500 count:0 mapcount:0 mapping:  (null) index:0x0
  flags: 0x96640253(locked|error|dirty|active|arch_1|reclaim|mlocked)
  page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
  bad because of flags:
  flags: 0x200041(locked|active|mlocked)
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 3.19.0-rc3-00007-g412f9ba-dirty #816
  Hardware name: Qualcomm (Flattened Device Tree)
    unwind_backtrace
    show_stack
    dump_stack
    bad_page
    free_pages_prepare
    free_hot_cold_page
    __free_pages
    free_highmem_page
    mem_init
    start_kernel
  Disabling lock debugging due to kernel taint

Removing the lower 2MB made the start of the lowmem zone to no longer be
page block aligned.  IFC6410 uses CONFIG_FLATMEM where alloc_node_mem_map
allocates memory for the mem_map.  alloc_node_mem_map will offset for
unaligned nodes with the assumption the pfn/page translation functions
will account for the offset.  The functions for CONFIG_FLATMEM do not
offset however, resulting in overrunning the memmap array.  Just use the
allocated memmap without any offset when running with CONFIG_FLATMEM to
avoid the overrun.
Signed-off-by: NLaura Abbott <laura@labbott.name>
Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
Reported-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Tested-by: NBjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Arnd Bergman <arnd@arndb.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Andy Gross <agross@codeaurora.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With x86_64 (config http://ozlabs.org/~akpm/config-akpm2.txt) and old gcc
(4.4.4), drivers/base/node.c:node_read_meminfo() is using 2344 bytes of
stack.  Uninlining node_page_state() reduces this to 440 bytes.

The stack consumption issue is fixed by newer gcc (4.8.4) however with
that compiler this patch reduces the node.o text size from 7314 bytes to
4578.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make __install_special_mapping() args order match the caller, so the
caller can pass their register args directly to callee with no touch.

For most of architectures, args (at least the first 5th args) are in
registers, so this change will have effect on most of architectures.

For -O2, __install_special_mapping() may be inlined under most of
architectures, but for -Os, it should not. So this change can get a
little better performance for -Os, at least.
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

(1) For !CONFIG_BUG cases, the bug call is a no-op, so we couldn't
    care less and the change is ok.

(2) ppc and mips, which HAVE_ARCH_BUG_ON, do not rely on branch
    predictions as it seems to be pointless[1] and thus callers should not
    be trying to push an optimization in the first place.

(3) For CONFIG_BUG and !HAVE_ARCH_BUG_ON cases, BUG_ON() contains an
    unlikely compiler flag already.

Hence, we can drop unlikely behind BUG_ON().

[1] http://lkml.iu.edu/hypermail/linux/kernel/1101.3/02289.htmlSigned-off-by: NGeliang Tang <geliangtang@163.com>
Acked-by: NDavidlohr Bueso <dave@stgolabs.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When fget() fails we can return -EBADF directly.
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is still a little better to remove it, although it should be skipped
by "-O2".

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>=0A=
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This came up when implementing HIHGMEM/PAE40 for ARC.  The kmap() /
kmap_atomic() generated code seemed needlessly bloated due to the way
PageHighMem() macro is implemented.  It derives the exact zone for page
and then does pointer subtraction with first zone to infer the zone_type.
The pointer arithmatic in turn generates the code bloat.

PageHighMem(page)
  is_highmem(page_zone(page))
     zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones

Instead use is_highmem_idx() to work on zone_type available in page flags

   ----- Before -----
80756348:	mov_s      r13,r0
8075634a:	ld_s       r2,[r13,0]
8075634c:	lsr_s      r2,r2,30
8075634e:	mpy        r2,r2,0x2a4
80756352:	add_s      r2,r2,0x80aef880
80756358:	ld_s       r3,[r2,28]
8075635a:	sub_s      r2,r2,r3
8075635c:	breq       r2,0x2a4,80756378 <kmap+0x48>
80756364:	breq       r2,0x548,80756378 <kmap+0x48>

   ----- After  -----
80756330:	mov_s      r13,r0
80756332:	ld_s       r2,[r13,0]
80756334:	lsr_s      r2,r2,30
80756336:	sub_s      r2,r2,1
80756338:	brlo       r2,2,80756348 <kmap+0x30>

For x86 defconfig build (32 bit only) it saves around 900 bytes.
For ARC defconfig with HIGHMEM, it saved around 2K bytes.

   ---->8-------
./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post
add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934)
function                                     old     new   delta
saveable_page                                162     154      -8
saveable_highmem_page                        154     146      -8
skb_gro_reset_offset                         147     131     -16
...
...
__change_page_attr_set_clr                  1715    1678     -37
setup_data_read                              434     394     -40
mon_bin_event                               1967    1927     -40
swsusp_save                                 1148    1105     -43
_set_pages_array                             549     493     -56
   ---->8-------

e.g. For ARC kmap()
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jennifer Herbert <jennifer.herbert@citrix.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Both "child->mm == mm" and "p->mm != mm" checks in oom_kill_process() are
wrong.  task->mm can be NULL if the task is the exited group leader.  This
means in particular that "kill sharing same memory" loop can miss a
process with a zombie leader which uses the same ->mm.

Note: the process_has_mm(child, p->mm) check is still not 100% correct,
p->mm can be NULL too.  This is minor, but probably deserves a fix or a
comment anyway.

[akpm@linux-foundation.org: document process_shares_mm() a bit]
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Kyle Walker <kwalker@redhat.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Purely cosmetic, but the complex "if" condition looks annoying to me.
Especially because it is not consistent with OOM_SCORE_ADJ_MIN check
which adds another if/continue.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Kyle Walker <kwalker@redhat.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The fatal_signal_pending() was added to suppress unnecessary "sharing same
memory" message, but it can't 100% help anyway because it can be
false-negative; SIGKILL can be already dequeued.

And worse, it can be false-positive due to exec or coredump.  exec is
mostly fine, but coredump is not.  It is possible that the group leader
has the pending SIGKILL because its sub-thread originated the coredump, in
this case we must not skip this process.

We could probably add the additional ->group_exit_task check but this
patch just removes the wrong check along with pr_info().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Kyle Walker <kwalker@redhat.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Cosmetic, but expand_upwards() and expand_downwards() overuse vma->vm_mm,
a local variable makes sense imho.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"mm->locked_vm += grow" and vm_stat_account() in acct_stack_growth() are
not safe; multiple threads using the same ->mm can do this at the same
time trying to expans different vma's under down_read(mmap_sem).  This
means that one of the "locked_vm += grow" changes can be lost and we can
miss munlock_vma_pages_all() later.

Move this code into the caller(s) under mm->page_table_lock.  All other
updates to ->locked_vm hold mmap_sem for writing.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the user set "movablecore=xx" to a large number, corepages will
overflow.  Fix the problem.
Signed-off-by: NXishi Qiu <qiuxishi@huawei.com>
Reviewed-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: NTang Chen <tangchen@cn.fujitsu.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In zone_reclaimable_pages(), `nr' is returned by a function which is
declared as returning "unsigned long", so declare it such.  Negative
values are meaningless here.

In zone_pagecache_reclaimable() we should also declare `delta' and
`nr_pagecache_reclaimable' as being unsigned longs because they're used to
store the values returned by zone_page_state() and
zone_unmapped_file_pages() which also happen to return unsigned integers.

[akpm@linux-foundation.org: make zone_pagecache_reclaimable() return ulong rather than long]
Signed-off-by: NAlexandru Moise <00moses.alexander00@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The oom killer takes task_lock() in a couple of places solely to protect
printing the task's comm.

A process's comm, including current's comm, may change due to
/proc/pid/comm or PR_SET_NAME.

The comm will always be NULL-terminated, so the worst race scenario would
only be during update.  We can tolerate a comm being printed that is in
the middle of an update to avoid taking the lock.

Other locations in the kernel have already dropped task_lock() when
printing comm, so this is consistent.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Suggested-by: NOleg Nesterov <oleg@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Compaction returns prematurely with COMPACT_PARTIAL when contended or has
fatal signal pending.  This is ok for the callers, but might be misleading
in the traces, as the usual reason to return COMPACT_PARTIAL is that we
think the allocation should succeed.  After this patch we distinguish the
premature ending condition in the mm_compaction_finished and
mm_compaction_end tracepoints.

The contended status covers the following reasons:
- lock contention or need_resched() detected in async compaction
- fatal signal pending
- too many pages isolated in the zone (only for async compaction)
Further distinguishing the exact reason seems unnecessary for now.
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some compaction tracepoints use zone->name to print which zone is being
compacted.  This works for in-kernel printing, but not userspace trace
printing of raw captured trace such as via trace-cmd report.

This patch uses zone_idx() instead of zone->name as the raw value, and
when printing, converts the zone_type to string using the appropriate EM()
macros and some ugly tricks to overcome the problem that half the values
depend on CONFIG_ options and one does not simply use #ifdef inside of
#define.

trace-cmd output before:
transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
zone=ffffffff81815d7a order=9 ret=partial

after:
transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
zone=Normal   order=9 ret=partial
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some compaction tracepoints convert the integer return values to strings
using the compaction_status_string array.  This works for in-kernel
printing, but not userspace trace printing of raw captured trace such as
via trace-cmd report.

This patch converts the private array to appropriate tracepoint macros
that result in proper userspace support.

trace-cmd output before:
transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
  zone=ffffffff81815d7a order=9 ret=

after:
transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
  zone=ffffffff81815d7a order=9 ret=partial
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

oom_kill_process() sends SIGKILL to other thread groups sharing victim's
mm.  But printing

  "Kill process %d (%s) sharing same memory\n"

lines makes no sense if they already have pending SIGKILL.  This patch
reduces the "Kill process" lines by printing that line with info level
only if SIGKILL is not pending.
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At the for_each_process() loop in oom_kill_process(), we are comparing
address of OOM victim's mm without holding a reference to that mm.  If
there are a lot of processes to compare or a lot of "Kill process %d (%s)
sharing same memory" messages to print, for_each_process() loop could take
very long time.

It is possible that meanwhile the OOM victim exits and releases its mm,
and then mm is allocated with the same address and assigned to some
unrelated process.  When we hit such race, the unrelated process will be
killed by error.  To make sure that the OOM victim's mm does not go away
until for_each_process() loop finishes, get a reference on the OOM
victim's mm before calling task_unlock(victim).

[oleg@redhat.com: several fixes]
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>