linux.git/mm/memory-failure.c, branch v2.6.38

thp: fix unsuitable behavior for hwpoisoned tail page

2011-02-03T00:03:19+00:00

When a tail page of THP is poisoned, memory-failure will do nothing except
setting PG_hwpoison, while the expected behavior is that the process, who
is using the poisoned tail page, should be killed.

The above problem is caused by lru check of the poisoned tail page of THP.
Because PG_lru flag is only set on the head page of THP, the check always
consider the poisoned tail page as NON lru page.

So the lru check for the tail page of THP should be avoided, as like as
hugetlb.

This patch adds !PageTransCompound() before lru check for THP, because of
the check (!PageHuge() && !PageTransCompound()) the whole branch could be
optimized away at build time when both hugetlbfs and THP are set with "N"
(or in archs not supporting either of those).

[akpm@linux-foundation.org: fix unrelated typo in shake_page() comment]
Signed-off-by: Jin Dongming 
Reviewed-by: Hidetoshi Seto 
Cc: Andrea Arcangeli 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: fix the wrong reported address of hwpoisoned hugepages

2011-02-03T00:03:19+00:00

When the tail page of THP is poisoned, the head page will be poisoned too.
 And the wrong address, address of head page, will be sent with sigbus
always.

So when the poisoned page is used by Guest OS which is running on KVM,
after the address changing(hva->gpa) by qemu, the unexpected process on
Guest OS will be killed by sigbus.

What we expected is that the process using the poisoned tail page could be
killed on Guest OS, but not that the process using the healthy head page
is killed.

Since it is not good to poison the healthy page, avoid poisoning other
than the page which is really poisoned.
  (While we poison all pages in a huge page in case of hugetlb,
   we can do this for THP thanks to split_huge_page().)

Here we fix two parts:
  1. Isolate the poisoned page only to make sure
     the reported address is the address of poisoned page.
  2. make the poisoned page work as the poisoned regular page.

[akpm@linux-foundation.org: fix spello in comment]
Signed-off-by: Jin Dongming 
Reviewed-by: Hidetoshi Seto 
Cc: Andrea Arcangeli 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: fix splitting of hwpoisoned hugepages

2011-02-03T00:03:19+00:00

The poisoned THP is now split with split_huge_page() in
collect_procs_anon().  If kmalloc() is failed in collect_procs(),
split_huge_page() could not be called.  And the work after
split_huge_page() for collecting the processes using poisoned page will
not be done, too.  So the processes using the poisoned page could not be
killed.

The condition becomes worse when CONFIG_DEBUG_VM == "Y".  Because the
poisoned THP could not be split, system panic will be caused by
VM_BUG_ON(PageTransHuge(page)) in try_to_unmap().

This patch does:
  1. move split_huge_page() to the place before collect_procs().
     This can be sure the failure of splitting THP is caused by itself.
  2. when splitting THP is failed, stop the operations after it.
     This can avoid unexpected system panic or non sense works.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jin Dongming 
Reviewed-by: Hidetoshi Seto 
Cc: Andrea Arcangeli 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/migration: fix page corruption during hugepage migration

2011-02-03T00:03:18+00:00

If migrate_huge_page by memory-failure fails , it calls put_page in itself
to decrease page reference and caller of migrate_huge_page also calls
putback_lru_pages.  It can do double free of page so it can make page
corruption on page holder.

In addtion, clean of pages on caller is consistent behavior with
migrate_pages by cf608ac19c ("mm: compaction: fix COMPACTPAGEFAILED
counting").

Signed-off-by: Minchan Kim 
Cc: Andrea Arcangeli 
Cc: Christoph Lameter 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: when migrate_pages returns 0, all pages must have been released

2011-02-03T00:03:18+00:00

In some cases migrate_pages could return zero while still leaving a few
pages in the pagelist (and some caller wouldn't notice it has to call
putback_lru_pages after commit cf608ac19c9 ("mm: compaction: fix
COMPACTPAGEFAILED counting")).

Add one missing putback_lru_pages not added by commit cf608ac19c95 ("mm:
compaction: fix COMPACTPAGEFAILED counting").

Signed-off-by: Andrea Arcangeli 
Signed-off-by: Minchan Kim 
Reviewed-by: Minchan Kim 
Cc: Christoph Lameter 
Acked-by: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: compound_trans_order

2011-01-14T01:32:47+00:00

Read compound_trans_order safe. Noop for CONFIG_TRANSPARENT_HUGEPAGE=n.

Signed-off-by: Andrea Arcangeli 
Cc: Daisuke Nishimura 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: fix memory-failure hugetlbfs vs THP collision

2011-01-14T01:32:47+00:00

hugetlbfs was changed to allow memory failure to migrate the hugetlbfs
pages and that broke THP as split_huge_page was then called on hugetlbfs
pages too.

compound_head/order was also run unsafe on THP pages that can be splitted
at any time.

All compound_head() invocations in memory-failure.c that are run on pages
that aren't pinned and that can be freed and reused from under us (while
compound_head is running) are buggy because compound_head can return a
dangling pointer, but I'm not fixing this as this is a generic
memory-failure bug not specific to THP but it applies to hugetlbfs too, so
I can fix it later after THP is merged upstream.

Signed-off-by: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: split_huge_page paging

2011-01-14T01:32:41+00:00

Paging logic that splits the page before it is unmapped and added to swap
to ensure backwards compatibility with the legacy swap code.  Eventually
swap should natively pageout the hugepages to increase performance and
decrease seeking and fragmentation of swap space.  swapoff can just skip
over huge pmd as they cannot be part of swap yet.  In add_to_swap be
careful to split the page only if we got a valid swap entry so we don't
split hugepages with a full swap.

In theory we could split pages before isolating them during the lru scan,
but for khugepaged to be safe, I'm relying on either mmap_sem write mode,
or PG_lock taken, so split_huge_page has to run either with mmap_sem
read/write mode or PG_lock taken.  Calling it from isolate_lru_page would
make locking more complicated, in addition to that split_huge_page would
deadlock if called by __isolate_lru_page because it has to take the lru
lock to add the tail pages.

Signed-off-by: Andrea Arcangeli 
Acked-by: Mel Gorman 
Acked-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migration: allow migration to operate asynchronously and avoid synchronous compaction in the faster path

2011-01-14T01:32:34+00:00

Migration synchronously waits for writeback if the initial passes fails.
Callers of memory compaction do not necessarily want this behaviour if the
caller is latency sensitive or expects that synchronous migration is not
going to have a significantly better success rate.

This patch adds a sync parameter to migrate_pages() allowing the caller to
indicate if wait_on_page_writeback() is allowed within migration or not.
For reclaim/compaction, try_to_compact_pages() is first called
asynchronously, direct reclaim runs and then try_to_compact_pages() is
called synchronously as there is a greater expectation that it'll succeed.

[akpm@linux-foundation.org: build/merge fix]
Signed-off-by: Mel Gorman 
Cc: Andrea Arcangeli 
Cc: KOSAKI Motohiro 
Cc: Rik van Riel 
Acked-by: Johannes Weiner 
Cc: Andy Whitcroft 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mem-hotplug: introduce {un}lock_memory_hotplug()

2010-12-02T22:51:15+00:00

Presently hwpoison is using lock_system_sleep() to prevent a race with
memory hotplug.  However lock_system_sleep() is a no-op if
CONFIG_HIBERNATION=n.  Therefore we need a new lock.

Signed-off-by: KOSAKI Motohiro 
Cc: Andi Kleen 
Cc: Kamezawa Hiroyuki 
Suggested-by: Hugh Dickins 
Acked-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds