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  1. 06 3月, 2012 2 次提交
  3. 01 3月, 2012 1 次提交
    • T
      memblock: Fix size aligning of memblock_alloc_base_nid() · 847854f5
      由 Tejun Heo 提交于 
      memblock allocator aligns @size to @align to reduce the amount
of fragmentation.  Commit:

 7bd0b0f0 ("memblock: Reimplement memblock allocation using reverse free area iterator")

Broke it by incorrectly relocating @size aligning to
memblock_find_in_range_node().  As the aligned size is not
propagated back to memblock_alloc_base_nid(), the actually
reserved size isn't aligned.

While this increases memory use for memblock reserved array,
this shouldn't cause any critical failure; however, it seems
that the size aligning was hiding a use-beyond-allocation bug in
sparc64 and losing the aligning causes boot failure.

The underlying problem is currently being debugged but this is a
proper fix in itself, it's already pretty late in -rc cycle for
boot failures and reverting the change for debugging isn't
difficult. Restore the size aligning moving it to
memblock_alloc_base_nid().
Reported-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120228205621.GC3252@dhcp-172-17-108-109.mtv.corp.google.comSigned-off-by: NIngo Molnar <mingo@elte.hu>
LKML-Reference: <alpine.SOC.1.00.1202130942030.1488@math.ut.ee>
      847854f5
  5. 25 2月, 2012 3 次提交
  7. 14 2月, 2012 1 次提交
  9. 09 2月, 2012 2 次提交
    • H
      mm: fix UP THP spin_is_locked BUGs · b9980cdc
      由 Hugh Dickins 提交于 
      Fix CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_SMP=n CONFIG_DEBUG_VM=y
CONFIG_DEBUG_SPINLOCK=n kernel: spin_is_locked() is then always false,
and so triggers some BUGs in Transparent HugePage codepaths.

asm-generic/bug.h mentions this problem, and provides a WARN_ON_SMP(x);
but being too lazy to add VM_BUG_ON_SMP, BUG_ON_SMP, WARN_ON_SMP_ONCE,
VM_WARN_ON_SMP_ONCE, just test NR_CPUS != 1 in the existing VM_BUG_ONs.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b9980cdc
    • M
      mm: compaction: check for overlapping nodes during isolation for migration · dc908600
      由 Mel Gorman 提交于 
      When isolating pages for migration, migration starts at the start of a
zone while the free scanner starts at the end of the zone.  Migration
avoids entering a new zone by never going beyond the free scanned.

Unfortunately, in very rare cases nodes can overlap.  When this happens,
migration isolates pages without the LRU lock held, corrupting lists
which will trigger errors in reclaim or during page free such as in the
following oops

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: [<ffffffff810f795c>] free_pcppages_bulk+0xcc/0x450
  PGD 1dda554067 PUD 1e1cb58067 PMD 0
  Oops: 0000 [#1] SMP
  CPU 37
  Pid: 17088, comm: memcg_process_s Tainted: G            X
  RIP: free_pcppages_bulk+0xcc/0x450
  Process memcg_process_s (pid: 17088, threadinfo ffff881c2926e000, task ffff881c2926c0c0)
  Call Trace:
    free_hot_cold_page+0x17e/0x1f0
    __pagevec_free+0x90/0xb0
    release_pages+0x22a/0x260
    pagevec_lru_move_fn+0xf3/0x110
    putback_lru_page+0x66/0xe0
    unmap_and_move+0x156/0x180
    migrate_pages+0x9e/0x1b0
    compact_zone+0x1f3/0x2f0
    compact_zone_order+0xa2/0xe0
    try_to_compact_pages+0xdf/0x110
    __alloc_pages_direct_compact+0xee/0x1c0
    __alloc_pages_slowpath+0x370/0x830
    __alloc_pages_nodemask+0x1b1/0x1c0
    alloc_pages_vma+0x9b/0x160
    do_huge_pmd_anonymous_page+0x160/0x270
    do_page_fault+0x207/0x4c0
    page_fault+0x25/0x30

The "X" in the taint flag means that external modules were loaded but but
is unrelated to the bug triggering.  The real problem was because the PFN
layout looks like this

  Zone PFN ranges:
    DMA      0x00000010 -> 0x00001000
    DMA32    0x00001000 -> 0x00100000
    Normal   0x00100000 -> 0x01e80000
  Movable zone start PFN for each node
  early_node_map[14] active PFN ranges
      0: 0x00000010 -> 0x0000009b
      0: 0x00000100 -> 0x0007a1ec
      0: 0x0007a354 -> 0x0007a379
      0: 0x0007f7ff -> 0x0007f800
      0: 0x00100000 -> 0x00680000
      1: 0x00680000 -> 0x00e80000
      0: 0x00e80000 -> 0x01080000
      1: 0x01080000 -> 0x01280000
      0: 0x01280000 -> 0x01480000
      1: 0x01480000 -> 0x01680000
      0: 0x01680000 -> 0x01880000
      1: 0x01880000 -> 0x01a80000
      0: 0x01a80000 -> 0x01c80000
      1: 0x01c80000 -> 0x01e80000

The fix is straight-forward.  isolate_migratepages() has to make a
similar check to isolate_freepage to ensure that it never isolates pages
from a zone it does not hold the LRU lock for.

This was discovered in a 3.0-based kernel but it affects 3.1.x, 3.2.x
and current mainline.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMichal Nazarewicz <mina86@mina86.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dc908600
  11. 04 2月, 2012 5 次提交
    • M
      mm: compaction: check pfn_valid when entering a new MAX_ORDER_NR_PAGES block... · 0bf380bc
      由 Mel Gorman 提交于 
      mm: compaction: check pfn_valid when entering a new MAX_ORDER_NR_PAGES block during isolation for migration

When isolating for migration, migration starts at the start of a zone
which is not necessarily pageblock aligned.  Further, it stops isolating
when COMPACT_CLUSTER_MAX pages are isolated so migrate_pfn is generally
not aligned.  This allows isolate_migratepages() to call pfn_to_page() on
an invalid PFN which can result in a crash.  This was originally reported
against a 3.0-based kernel with the following trace in a crash dump.

PID: 9902   TASK: d47aecd0  CPU: 0   COMMAND: "memcg_process_s"
 #0 [d72d3ad0] crash_kexec at c028cfdb
 #1 [d72d3b24] oops_end at c05c5322
 #2 [d72d3b38] __bad_area_nosemaphore at c0227e60
 #3 [d72d3bec] bad_area at c0227fb6
 #4 [d72d3c00] do_page_fault at c05c72ec
 #5 [d72d3c80] error_code (via page_fault) at c05c47a4
    EAX: 00000000  EBX: 000c0000  ECX: 00000001  EDX: 00000807  EBP: 000c0000
    DS:  007b      ESI: 00000001  ES:  007b      EDI: f3000a80  GS:  6f50
    CS:  0060      EIP: c030b15a  ERR: ffffffff  EFLAGS: 00010002
 #6 [d72d3cb4] isolate_migratepages at c030b15a
 #7 [d72d3d14] zone_watermark_ok at c02d26cb
 #8 [d72d3d2c] compact_zone at c030b8de
 #9 [d72d3d68] compact_zone_order at c030bba1
#10 [d72d3db4] try_to_compact_pages at c030bc84
#11 [d72d3ddc] __alloc_pages_direct_compact at c02d61e7
#12 [d72d3e08] __alloc_pages_slowpath at c02d66c7
#13 [d72d3e78] __alloc_pages_nodemask at c02d6a97
#14 [d72d3eb8] alloc_pages_vma at c030a845
#15 [d72d3ed4] do_huge_pmd_anonymous_page at c03178eb
#16 [d72d3f00] handle_mm_fault at c02f36c6
#17 [d72d3f30] do_page_fault at c05c70ed
#18 [d72d3fb0] error_code (via page_fault) at c05c47a4
    EAX: b71ff000  EBX: 00000001  ECX: 00001600  EDX: 00000431
    DS:  007b      ESI: 08048950  ES:  007b      EDI: bfaa3788
    SS:  007b      ESP: bfaa36e0  EBP: bfaa3828  GS:  6f50
    CS:  0073      EIP: 080487c8  ERR: ffffffff  EFLAGS: 00010202

It was also reported by Herbert van den Bergh against 3.1-based kernel
with the following snippet from the console log.

BUG: unable to handle kernel paging request at 01c00008
IP: [<c0522399>] isolate_migratepages+0x119/0x390
*pdpt = 000000002f7ce001 *pde = 0000000000000000

It is expected that it also affects 3.2.x and current mainline.

The problem is that pfn_valid is only called on the first PFN being
checked and that PFN is not necessarily aligned.  Lets say we have a case
like this

H = MAX_ORDER_NR_PAGES boundary
| = pageblock boundary
m = cc->migrate_pfn
f = cc->free_pfn
o = memory hole

H------|------H------|----m-Hoooooo|ooooooH-f----|------H

The migrate_pfn is just below a memory hole and the free scanner is beyond
the hole.  When isolate_migratepages started, it scans from migrate_pfn to
migrate_pfn+pageblock_nr_pages which is now in a memory hole.  It checks
pfn_valid() on the first PFN but then scans into the hole where there are
not necessarily valid struct pages.

This patch ensures that isolate_migratepages calls pfn_valid when
necessary.
Reported-by: NHerbert van den Bergh <herbert.van.den.bergh@oracle.com>
Tested-by: NHerbert van den Bergh <herbert.van.den.bergh@oracle.com>
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMichal Nazarewicz <mina86@mina86.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0bf380bc
    • S
      readahead: fix pipeline break caused by block plug · 3deaa719
      由 Shaohua Li 提交于 
      Herbert Poetzl reported a performance regression since 2.6.39.  The test
is a simple dd read, but with big block size.  The reason is:

T1: ra (A, A+128k), (A+128k, A+256k)
T2: lock_page for page A, submit the 256k
T3: hit page A+128K, ra (A+256k, A+384). the range isn't submitted
because of plug and there isn't any lock_page till we hit page A+256k
because all pages from A to A+256k is in memory
T4: hit page A+256k, ra (A+384, A+ 512). Because of plug, the range isn't
submitted again.
T5: lock_page A+256k, so (A+256k, A+512k) will be submitted. The task is
waitting for (A+256k, A+512k) finish.

There is no request to disk in T3 and T4, so readahead pipeline breaks.

We really don't need block plug for generic_file_aio_read() for buffered
I/O.  The readahead already has plug and has fine grained control when I/O
should be submitted.  Deleting plug for buffered I/O fixes the regression.

One side effect is plug makes the request size 256k, the size is 128k
without it.  This is because default ra size is 128k and not a reason we
need plug here.

Vivek said:

: We submit some readahead IO to device request queue but because of nested
: plug, queue never gets unplugged.  When read logic reaches a page which is
: not in page cache, it waits for page to be read from the disk
: (lock_page_killable()) and that time we flush the plug list.
:
: So effectively read ahead logic is kind of broken in parts because of
: nested plugging.  Removing top level plug (generic_file_aio_read()) for
: buffered reads, will allow unplugging queue earlier for readahead.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Reported-by: NHerbert Poetzl <herbert@13thfloor.at>
Tested-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3deaa719
    • C
      mm/filemap_xip.c: fix race condition in xip_file_fault() · 99f02ef1
      由 Carsten Otte 提交于 
      Fix a race condition that shows in conjunction with xip_file_fault() when
two threads of the same user process fault on the same memory page.

In this case, the race winner will install the page table entry and the
unlucky loser will cause an oops: xip_file_fault calls vm_insert_pfn (via
vm_insert_mixed) which drops out at this check:

	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

The resulting -EBUSY return value will trigger a BUG_ON() in
xip_file_fault.

This fix simply considers the fault as fixed in this case, because the
race winner has successfully installed the pte.

[akpm@linux-foundation.org: use conventional (and consistent) comment layout]
Reported-by: NDavid Sadler <dsadler@us.ibm.com>
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Reported-by: NLouis Alex Eisner <leisner@cs.ucsd.edu>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      99f02ef1
    • A
      mm/memcontrol.c: fix warning with CONFIG_NUMA=n · 82b3f2a7
      由 Andrew Morton 提交于 
      mm/memcontrol.c: In function 'memcg_check_events':
mm/memcontrol.c:779: warning: unused variable 'do_numainfo'
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: N"Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      82b3f2a7
    • K
      mm: postpone migrated page mapping reset · 35512eca
      由 Konstantin Khlebnikov 提交于 
      Postpone resetting page->mapping until the final remove_migration_ptes().
Otherwise the expression PageAnon(migration_entry_to_page(entry)) does not
work.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      35512eca
  13. 03 2月, 2012 1 次提交
  15. 01 2月, 2012 1 次提交
  17. 24 1月, 2012 7 次提交
    • K
      mm: fix rss count leakage during migration · 9f9f1acd
      由 Konstantin Khlebnikov 提交于 
      Memory migration fills a pte with a migration entry and it doesn't
update the rss counters.  Then it replaces the migration entry with the
new page (or the old one if migration failed).  But between these two
passes this pte can be unmaped, or a task can fork a child and it will
get a copy of this migration entry.  Nobody accounts for this in the rss
counters.

This patch properly adjust rss counters for migration entries in
zap_pte_range() and copy_one_pte().  Thus we avoid extra atomic
operations on the migration fast-path.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9f9f1acd
    • H
      SHM_UNLOCK: fix Unevictable pages stranded after swap · 24513264
      由 Hugh Dickins 提交于 
      Commit cc39c6a9 ("mm: account skipped entries to avoid looping in
find_get_pages") correctly fixed an infinite loop; but left a problem
that find_get_pages() on shmem would return 0 (appearing to callers to
mean end of tree) when it meets a run of nr_pages swap entries.

The only uses of find_get_pages() on shmem are via pagevec_lookup(),
called from invalidate_mapping_pages(), and from shmctl SHM_UNLOCK's
scan_mapping_unevictable_pages().  The first is already commented, and
not worth worrying about; but the second can leave pages on the
Unevictable list after an unusual sequence of swapping and locking.

Fix that by using shmem_find_get_pages_and_swap() (then ignoring the
swap) instead of pagevec_lookup().

But I don't want to contaminate vmscan.c with shmem internals, nor
shmem.c with LRU locking.  So move scan_mapping_unevictable_pages() into
shmem.c, renaming it shmem_unlock_mapping(); and rename
check_move_unevictable_page() to check_move_unevictable_pages(), looping
down an array of pages, oftentimes under the same lock.

Leave out the "rotate unevictable list" block: that's a leftover from
when this was used for /proc/sys/vm/scan_unevictable_pages, whose flawed
handling involved looking at pages at tail of LRU.

Was there significance to the sequence first ClearPageUnevictable, then
test page_evictable, then SetPageUnevictable here? I think not, we're
under LRU lock, and have no barriers between those.
Signed-off-by: NHugh Dickins <hughd@google.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: <stable@vger.kernel.org> [back to 3.1 but will need respins]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      24513264
    • H
      SHM_UNLOCK: fix long unpreemptible section · 85046579
      由 Hugh Dickins 提交于 
      scan_mapping_unevictable_pages() is used to make SysV SHM_LOCKed pages
evictable again once the shared memory is unlocked.  It does this with
pagevec_lookup()s across the whole object (which might occupy most of
memory), and takes 300ms to unlock 7GB here.  A cond_resched() every
PAGEVEC_SIZE pages would be good.

However, KOSAKI-san points out that this is called under shmem.c's
info->lock, and it's also under shm.c's shm_lock(), both spinlocks.
There is no strong reason for that: we need to take these pages off the
unevictable list soonish, but those locks are not required for it.

So move the call to scan_mapping_unevictable_pages() from shmem.c's
unlock handling up to shm.c's unlock handling.  Remove the recently
added barrier, not needed now we have spin_unlock() before the scan.

Use get_file(), with subsequent fput(), to make sure we have a reference
to mapping throughout scan_mapping_unevictable_pages(): that's something
that was previously guaranteed by the shm_lock().

Remove shmctl's lru_add_drain_all(): we don't fault in pages at SHM_LOCK
time, and we lazily discover them to be Unevictable later, so it serves
no purpose for SHM_LOCK; and serves no purpose for SHM_UNLOCK, since
pages still on pagevec are not marked Unevictable.

The original code avoided redundant rescans by checking VM_LOCKED flag
at its level: now avoid them by checking shp's SHM_LOCKED.

The original code called scan_mapping_unevictable_pages() on a locked
area at shm_destroy() time: perhaps we once had accounting cross-checks
which required that, but not now, so skip the overhead and just let
inode eviction deal with them.

Put check_move_unevictable_page() and scan_mapping_unevictable_pages()
under CONFIG_SHMEM (with stub for the TINY case when ramfs is used),
more as comment than to save space; comment them used for SHM_UNLOCK.
Signed-off-by: NHugh Dickins <hughd@google.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      85046579
    • H
      mm/hugetlb.c: undo change to page mapcount in fault handler · 409eb8c2
      由 Hillf Danton 提交于 
      Page mapcount should be updated only if we are sure that the page ends
up in the page table otherwise we would leak if we couldn't COW due to
reservations or if idx is out of bounds.
Signed-off-by: NHillf Danton <dhillf@gmail.com>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      409eb8c2
    • J
      mm: memcg: update the correct soft limit tree during migration · 6568d4a9
      由 Johannes Weiner 提交于 
      end_migration() passes the old page instead of the new page to commit
the charge.  This page descriptor is not used for committing itself,
though, since we also pass the (correct) page_cgroup descriptor.  But
it's used to find the soft limit tree through the page's zone, so the
soft limit tree of the old page's zone is updated instead of that of the
new page's, which might get slightly out of date until the next charge
reaches the ratelimit point.

This glitch has been present since 5564e88b ("memcg: condense
page_cgroup-to-page lookup points").

This fixes a bug that I introduced in 2.6.38.  It's benign enough (to my
knowledge) that we probably don't want this for stable.
Reported-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NKirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6568d4a9
    • M
      mm: __count_immobile_pages(): make sure the node is online · 656a0706
      由 Michal Hocko 提交于 
      page_zone() requires an online node otherwise we are accessing NULL
NODE_DATA.  This is not an issue at the moment because node_zones are
located at the structure beginning but this might change in the future
so better be careful about that.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      656a0706
    • M
      mm: fix NULL ptr dereference in __count_immobile_pages · 687875fb
      由 Michal Hocko 提交于 
      Fix the following NULL ptr dereference caused by

  cat /sys/devices/system/memory/memory0/removable

Pid: 13979, comm: sed Not tainted 3.0.13-0.5-default #1 IBM BladeCenter LS21 -[7971PAM]-/Server Blade
RIP: __count_immobile_pages+0x4/0x100
Process sed (pid: 13979, threadinfo ffff880221c36000, task ffff88022e788480)
Call Trace:
  is_pageblock_removable_nolock+0x34/0x40
  is_mem_section_removable+0x74/0xf0
  show_mem_removable+0x41/0x70
  sysfs_read_file+0xfe/0x1c0
  vfs_read+0xc7/0x130
  sys_read+0x53/0xa0
  system_call_fastpath+0x16/0x1b

We are crashing because we are trying to dereference NULL zone which
came from pfn=0 (struct page ffffea0000000000). According to the boot
log this page is marked reserved:
e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved)

and early_node_map confirms that:
early_node_map[3] active PFN ranges
    1: 0x00000010 -> 0x0000009c
    1: 0x00000100 -> 0x000bffa3
    1: 0x00100000 -> 0x00240000

The problem is that memory_present works in PAGE_SECTION_MASK aligned
blocks so the reserved range sneaks into the the section as well.  This
also means that free_area_init_node will not take care of those reserved
pages and they stay uninitialized.

When we try to read the removable status we walk through all available
sections and hope that the zone is valid for all pages in the section.
But this is not true in this case as the zone and nid are not initialized.

We have only one node in this particular case and it is marked as node=1
(rather than 0) and that made the problem visible because page_to_nid will
return 0 and there are no zones on the node.

Let's check that the zone is valid and that the given pfn falls into its
boundaries and mark the section not removable.  This might cause some
false positives, probably, but we do not have any sane way to find out
whether the page is reserved by the platform or it is just not used for
whatever other reasons.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      687875fb
  19. 23 1月, 2012 1 次提交
  21. 21 1月, 2012 3 次提交
  23. 17 1月, 2012 1 次提交
  25. 16 1月, 2012 1 次提交
  27. 13 1月, 2012 11 次提交