Commit Graph

555102 Commits

Author SHA1 Message Date
Hugh Dickins cf4b769abb mm: page migration avoid touching newpage until no going back
We have had trouble in the past from the way in which page migration's
newpage is initialized in dribs and drabs - see commit 8bdd638091 ("mm:
fix direct reclaim writeback regression") which proposed a cleanup.

We have no actual problem now, but I think the procedure would be clearer
(and alternative get_new_page pools safer to implement) if we assert that
newpage is not touched until we are sure that it's going to be used -
except for taking the trylock on it in __unmap_and_move().

So shift the early initializations from move_to_new_page() into
migrate_page_move_mapping(), mapping and NULL-mapping paths.  Similarly
migrate_huge_page_move_mapping(), but its NULL-mapping path can just be
deleted: you cannot reach hugetlbfs_migrate_page() with a NULL mapping.

Adjust stages 3 to 8 in the Documentation file accordingly.

Signed-off-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 470f119f01 mm: page migration use migration entry for swapcache too
Hitherto page migration has avoided using a migration entry for a
swapcache page mapped into userspace, apparently for historical reasons.
So any page blessed with swapcache would entail a minor fault when it's
next touched, which page migration otherwise tries to avoid.  Swapcache in
an mlocked area is rare, so won't often matter, but still better fixed.

Just rearrange the block in try_to_unmap_one(), to handle TTU_MIGRATION
before checking PageAnon, that's all (apart from some reindenting).

Well, no, that's not quite all: doesn't this by the way fix a soft_dirty
bug, that page migration of a file page was forgetting to transfer the
soft_dirty bit?  Probably not a serious bug: if I understand correctly,
soft_dirty afficionados usually have to handle file pages separately
anyway; but we publish the bit in /proc/<pid>/pagemap on file mappings as
well as anonymous, so page migration ought not to perturb it.

Signed-off-by: Hugh 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>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 03f15c86c8 mm: simplify page migration's anon_vma comment and flow
__unmap_and_move() contains a long stale comment on page_get_anon_vma()
and PageSwapCache(), with an odd control flow that's hard to follow.
Mostly this reflects our confusion about the lifetime of an anon_vma, in
the early days of page migration, before we could take a reference to one.
 Nowadays this seems quite straightforward: cut it all down to essentials.

I cannot see the relevance of swapcache here at all, so don't treat it any
differently: I believe the old comment reflects in part our anon_vma
confusions, and in part the original v2.6.16 page migration technique,
which used actual swap to migrate anon instead of swap-like migration
entries.  Why should a swapcache page not be migrated with the aid of
migration entry ptes like everything else?  So lose that comment now, and
enable migration entries for swapcache in the next patch.

Signed-off-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 5c3f9a6737 mm: page migration remove_migration_ptes at lock+unlock level
Clean up page migration a little more by calling remove_migration_ptes()
from the same level, on success or on failure, from __unmap_and_move() or
from unmap_and_move_huge_page().

Don't reset page->mapping of a PageAnon old page in move_to_new_page(),
leave that to when the page is freed.  Except for here in page migration,
it has been an invariant that a PageAnon (bit set in page->mapping) page
stays PageAnon until it is freed, and I think we're safer to keep to that.

And with the above rearrangement, it's necessary because zap_pte_range()
wants to identify whether a migration entry represents a file or an anon
page, to update the appropriate rss stats without waiting on it.

Signed-off-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 7db7671f83 mm: page migration trylock newpage at same level as oldpage
Clean up page migration a little by moving the trylock of newpage from
move_to_new_page() into __unmap_and_move(), where the old page has been
locked.  Adjust unmap_and_move_huge_page() and balloon_page_migrate()
accordingly.

But make one kind-of-functional change on the way: whereas trylock of
newpage used to BUG() if it failed, now simply return -EAGAIN if so.
Cutting out BUG()s is good, right?  But, to be honest, this is really to
extend the usefulness of the custom put_new_page feature, allowing a pool
of new pages to be shared perhaps with racing uses.

Use an "else" instead of that "skip_unmap" label.

Signed-off-by: Hugh 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: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 2def7424c9 mm: page migration use the put_new_page whenever necessary
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: Hugh 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: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 14e0f9bcc9 mm: correct a couple of page migration comments
It's migrate.c not migration,c, and nowadays putback_movable_pages() not
putback_lru_pages().

Signed-off-by: Hugh 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: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 45637bab30 mm: rename mem_cgroup_migrate to mem_cgroup_replace_page
After v4.3's commit 0610c25daa ("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: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 51afb12ba8 mm: page migration fix PageMlocked on migrated pages
Commit e6c509f854 ("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: Hugh 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: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins b87537d9e2 mm: rmap use pte lock not mmap_sem to set PageMlocked
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
48ec833b78 ("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: Hugh 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: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Hugh Dickins 7a14239a8f mm Documentation: undoc non-linear vmas
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: Hugh 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: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov 706874e909 mm: do not inc NR_PAGETABLE if ptlock_init failed
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: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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>
2015-11-05 19:34:48 -08:00
Laurent Dufour 5d3875a01e mm: clear_soft_dirty_pmd() requires THP
Don't build clear_soft_dirty_pmd() if transparent huge pages are not
enabled.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: Aneesh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Laurent Dufour 326c2597a3 mm: clear pte in clear_soft_dirty()
As mentioned in the commit 56eecdb912 ("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: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: Aneesh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrea Arcangeli c8f95ed1a9 ksm: unstable_tree_search_insert error checking cleanup
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: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrea Arcangeli 85c6e8dd23 ksm: use find_mergeable_vma in try_to_merge_with_ksm_page
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: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrea Arcangeli 98666f8a25 ksm: use the helper method to do the hlist_empty check
This just uses the helper function to cleanup the assumption on the
hlist_node internals.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrea Arcangeli f2e5ff85ed ksm: don't fail stable tree lookups if walking over stale stable_nodes
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: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrea Arcangeli ad12695f17 ksm: add cond_resched() to the rmap_walks
While at it add it to the file and anon walks too.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Petr Holasek <pholasek@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov df4065516b memcg: simplify and inline __mem_cgroup_from_kmem
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: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov f3ccb2c422 memcg: unify slab and other kmem pages charging
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: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vladimir Davydov d05e83a6f8 memcg: simplify charging kmem pages
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: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Xishi Qiu bde304bdf4 mm/page_alloc.c: skip ZONE_MOVABLE if required_kernelcore is larger than totalpages
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: Xishi Qiu <qiuxishi@huawei.com>
Reviewed-by: Yasuaki 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Davidlohr Bueso a2c1aad3b5 mm/vmacache: inline vmacache_valid_mm()
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: Davidlohr Bueso <dbueso@suse.de>
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>
2015-11-05 19:34:48 -08:00
yalin wang f7ae3a95ea include/linux/vm_event_item.h: change HIGHMEM_ZONE macro definition
Change HIGHMEM_ZONE to be the same as the DMA_ZONE macro.

Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Laura Abbott a1c34a3bf0 mm: Don't offset memmap for flatmem
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: Laura Abbott <laura@labbott.name>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Bjorn 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Andrew Morton c2d42c16ad mm/vmstat.c: uninline node_page_state()
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Chen Gang 27f28b972e mm/mmap.c: change __install_special_mapping() args order
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: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Geliang Tang c9427bc043 mm/nommu.c: drop unlikely inside BUG_ON()
(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.html

Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Chen Gang 1e3ee14b93 mm/mmap.c: do not initialize retval in mmap_pgoff()
When fget() fails we can return -EBADF directly.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Chen Gang e6ee219fdd mm/mmap.c: remove redundant statement "error = -ENOMEM"
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: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vineet Gupta 3ca65c19dd mm: optimize PageHighMem() check
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: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Michal 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Oleg Nesterov 4d7b3394f7 mm/oom_kill: fix the wrong task->mm == mm checks in oom_kill_process()
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: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Oleg Nesterov c319025a6c mm/oom_kill: cleanup the "kill sharing same memory" loop
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: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Oleg Nesterov 0c1b2d783c mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process()
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: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kyle Walker <kwalker@redhat.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Oleg Nesterov 0935781477 mm: add the "struct mm_struct *mm" local into
Cosmetic, but expand_upwards() and expand_downwards() overuse vma->vm_mm,
a local variable makes sense imho.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Oleg Nesterov 87e8827b37 mm: fix the racy mm->locked_vm change in
"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: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Xishi Qiu 9fd745d450 mm: fix overflow in find_zone_movable_pfns_for_nodes()
If the user set "movablecore=xx" to a large number, corepages will
overflow.  Fix the problem.

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Tang Chen <tangchen@cn.fujitsu.com>
Acked-by: David 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Alexandru Moise d031a15791 mm/vmscan.c: fix types of some locals
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: Alexandru Moise <00moses.alexander00@gmail.com>
Acked-by: Michal 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
David Rientjes da39da3a54 mm, oom: remove task_lock protecting comm printing
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: David Rientjes <rientjes@google.com>
Suggested-by: Oleg 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: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vlastimil Babka 2d1e10412c mm, compaction: distinguish contended status in tracepoints
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: Vlastimil 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vlastimil Babka 1743d05060 mm, compaction: export tracepoints zone names to userspace
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: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Steven 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Vlastimil Babka fa6c7b46aa mm, compaction: export tracepoints status strings to userspace
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: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Steven 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tetsuo Handa 840807a8f4 mm/oom_kill.c: suppress unnecessary "sharing same memory" message
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: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tetsuo Handa 880b768937 mm/oom_kill.c: fix potentially killing unrelated process
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: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Tetsuo Handa 426fb5e72d mm/oom_kill.c: reverse the order of setting TIF_MEMDIE and sending SIGKILL
It was confirmed that a local unprivileged user can consume all memory
reserves and hang up that system using time lag between the OOM killer
sets TIF_MEMDIE on an OOM victim and sends SIGKILL to that victim, for
printk() inside for_each_process() loop at oom_kill_process() can consume
many seconds when there are many thread groups sharing the same memory.

Before starting oom-depleter process:

    Node 0 DMA: 3*4kB (UM) 6*8kB (U) 4*16kB (UEM) 0*32kB 0*64kB 1*128kB (M) 2*256kB (EM) 2*512kB (UE) 2*1024kB (EM) 1*2048kB (E) 1*4096kB (M) = 9980kB
    Node 0 DMA32: 31*4kB (UEM) 27*8kB (UE) 32*16kB (UE) 13*32kB (UE) 14*64kB (UM) 7*128kB (UM) 8*256kB (UM) 8*512kB (UM) 3*1024kB (U) 4*2048kB (UM) 362*4096kB (UM) = 1503220kB

As of invoking the OOM killer:

    Node 0 DMA: 11*4kB (UE) 8*8kB (UEM) 6*16kB (UE) 2*32kB (EM) 0*64kB 1*128kB (U) 3*256kB (UEM) 2*512kB (UE) 3*1024kB (UEM) 1*2048kB (U) 0*4096kB = 7308kB
    Node 0 DMA32: 1049*4kB (UEM) 507*8kB (UE) 151*16kB (UE) 53*32kB (UEM) 83*64kB (UEM) 52*128kB (EM) 25*256kB (UEM) 11*512kB (M) 6*1024kB (UM) 1*2048kB (M) 0*4096kB = 44556kB

Between the thread group leader got TIF_MEMDIE and receives SIGKILL:

    Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
    Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB

The oom-depleter's thread group leader which got TIF_MEMDIE started
memset() in user space after the OOM killer set TIF_MEMDIE, and it was
free to abuse ALLOC_NO_WATERMARKS by TIF_MEMDIE for memset() in user space
until SIGKILL is delivered.  If SIGKILL is delivered before TIF_MEMDIE is
set, the oom-depleter can terminate without touching memory reserves.

Although the possibility of hitting this time lag is very small for 3.19
and earlier kernels because TIF_MEMDIE is set immediately before sending
SIGKILL, preemption or long interrupts (an extreme example is SysRq-t) can
step between and allow memory allocations which are not needed for
terminating the OOM victim.

Fixes: 83363b917a ("oom: make sure that TIF_MEMDIE is set under task_lock")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>	[4.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Yaowei Bai 13308ca9ef mm/memcontrol: make mem_cgroup_inactive_anon_is_low() return bool
Make mem_cgroup_inactive_anon_is_low return bool due to this particular
function only using either one or zero as its return value.

No functional change.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 19:34:48 -08:00
Yaowei Bai 42e2e45777 mm/vmscan: make inactive_anon/file_is_low return bool
Make inactive_anon/file_is_low return bool due to these particular
functions only using either one or zero as their return value.

No functional change.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
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>
2015-11-05 19:34:48 -08:00
Ebru Akagunduz 80f73b4b71 Documentation/vm/transhuge.txt: add information about max_ptes_swap
max_ptes_swap specifies how many pages can be brought in from swap when
collapsing a group of pages into a transparent huge page.

/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap

A higher value can cause excessive swap IO and waste memory.  A lower
value can prevent THPs from being collapsed, resulting fewer pages being
collapsed into THPs, and lower memory access performance.

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.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>
2015-11-05 19:34:48 -08:00
Jerome Marchand 3608de0787 mm/memcontrol.c: fix order calculation in try_charge()
Since commit 6539cc0538 ("mm: memcontrol: fold mem_cgroup_do_charge()"),
the order to pass to mem_cgroup_oom() is calculated by passing the
number of pages to get_order() instead of the expected size in bytes.
AFAICT, it only affects the value displayed in the oom warning message.
This patch fix this.

Michal said:

: We haven't noticed that just because the OOM is enabled only for page
: faults of order-0 (single page) and get_order work just fine.  Thanks for
: noticing this.  If we ever start triggering OOM on different orders this
: would be broken.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
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>
2015-11-05 19:34:48 -08:00