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  1. 22 11月, 2012 4 次提交
  3. 21 11月, 2012 7 次提交
  5. 20 11月, 2012 8 次提交
  7. 19 11月, 2012 8 次提交
  9. 18 11月, 2012 5 次提交
  11. 17 11月, 2012 8 次提交
    • D
      xfs: drop buffer io reference when a bad bio is built · d69043c4
      由 Dave Chinner 提交于 
      Error handling in xfs_buf_ioapply_map() does not handle IO reference
counts correctly. We increment the b_io_remaining count before
building the bio, but then fail to decrement it in the failure case.
This leads to the buffer never running IO completion and releasing
the reference that the IO holds, so at unmount we can leak the
buffer. This leak is captured by this assert failure during unmount:

XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/xfs_mount.c, line: 273

This is not a new bug - the b_io_remaining accounting has had this
problem for a long, long time - it's just very hard to get a
zero length bio being built by this code...

Further, the buffer IO error can be overwritten on a multi-segment
buffer by subsequent bio completions for partial sections of the
buffer. Hence we should only set the buffer error status if the
buffer is not already carrying an error status. This ensures that a
partial IO error on a multi-segment buffer will not be lost. This
part of the problem is a regression, however.

cc: <stable@vger.kernel.org>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      d69043c4
    • D
      xfs: fix broken error handling in xfs_vm_writepage · 3daed8bc
      由 Dave Chinner 提交于 
      When we shut down the filesystem, it might first be detected in
writeback when we are allocating a inode size transaction. This
happens after we have moved all the pages into the writeback state
and unlocked them. Unfortunately, if we fail to set up the
transaction we then abort writeback and try to invalidate the
current page. This then triggers are BUG() in block_invalidatepage()
because we are trying to invalidate an unlocked page.

Fixing this is a bit of a chicken and egg problem - we can't
allocate the transaction until we've clustered all the pages into
the IO and we know the size of it (i.e. whether the last block of
the IO is beyond the current EOF or not). However, we don't want to
hold pages locked for long periods of time, especially while we lock
other pages to cluster them into the write.

To fix this, we need to make a clear delineation in writeback where
errors can only be handled by IO completion processing. That is,
once we have marked a page for writeback and unlocked it, we have to
report errors via IO completion because we've already started the
IO. We may not have submitted any IO, but we've changed the page
state to indicate that it is under IO so we must now use the IO
completion path to report errors.

To do this, add an error field to xfs_submit_ioend() to pass it the
error that occurred during the building on the ioend chain. When
this is non-zero, mark each ioend with the error and call
xfs_finish_ioend() directly rather than building bios. This will
immediately push the ioends through completion processing with the
error that has occurred.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      3daed8bc
    • D
      xfs: fix attr tree double split corruption · 42e2976f
      由 Dave Chinner 提交于 
      In certain circumstances, a double split of an attribute tree is
needed to insert or replace an attribute. In rare situations, this
can go wrong, leaving the attribute tree corrupted. In this case,
the attr being replaced is the last attr in a leaf node, and the
replacement is larger so doesn't fit in the same leaf node.
When we have the initial condition of a node format attribute
btree with two leaves at index 1 and 2. Call them L1 and L2.  The
leaf L1 is completely full, there is not a single byte of free space
in it. L2 is mostly empty.  The attribute being replaced - call it X
- is the last attribute in L1.

The way an attribute replace is executed is that the replacement
attribute - call it Y - is first inserted into the tree, but has an
INCOMPLETE flag set on it so that list traversals ignore it. Once
this transaction is committed, a second transaction it run to
atomically mark Y as COMPLETE and X as INCOMPLETE, so that a
traversal will now find Y and skip X. Once that transaction is
committed, attribute X is then removed.

So, the initial condition is:

     +--------+     +--------+
     |   L1   |     |   L2   |
     | fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |
     | fsp: 0 |     | fsp: N |
     |--------|     |--------|
     | attr A |     | attr 1 |
     |--------|     |--------|
     | attr B |     | attr 2 |
     |--------|     |--------|
     ..........     ..........
     |--------|     |--------|
     | attr X |     | attr n |
     +--------+     +--------+

So now we go to replace X, and see that L1:fsp = 0 - it is full so
we can't insert Y in the same leaf. So we record the the location of
attribute X so we can track it for later use, then we split L1 into
L1 and L3 and reblance across the two leafs. We end with:

     +--------+     +--------+     +--------+
     |   L1   |     |   L3   |     |   L2   |
     | fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|
     | attr A |     | attr X |     | attr 1 |
     |--------|     +--------+     |--------|
     | attr B |                    | attr 2 |
     |--------|                    |--------|
     ..........                    ..........
     |--------|                    |--------|
     | attr W |                    | attr n |
     +--------+                    +--------+

And we track that the original attribute is now at L3:0.

We then try to insert Y into L1 again, and find that there isn't
enough room because the new attribute is larger than the old one.
Hence we have to split again to make room for Y. We end up with
this:

     +--------+     +--------+     +--------+     +--------+
     |   L1   |     |   L4   |     |   L3   |     |   L2   |
     | fwd: 4 |---->| fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 4 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|     |--------|
     | attr A |     | attr Y |     | attr X |     | attr 1 |
     |--------|     + INCOMP +     +--------+     |--------|
     | attr B |     +--------+                    | attr 2 |
     |--------|                                   |--------|
     ..........                                   ..........
     |--------|                                   |--------|
     | attr W |                                   | attr n |
     +--------+                                   +--------+

And now we have the new (incomplete) attribute @ L4:0, and the
original attribute at L3:0. At this point, the first transaction is
committed, and we move to the flipping of the flags.

This is where we are supposed to end up with this:

     +--------+     +--------+     +--------+     +--------+
     |   L1   |     |   L4   |     |   L3   |     |   L2   |
     | fwd: 4 |---->| fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 4 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|     |--------|
     | attr A |     | attr Y |     | attr X |     | attr 1 |
     |--------|     +--------+     + INCOMP +     |--------|
     | attr B |                    +--------+     | attr 2 |
     |--------|                                   |--------|
     ..........                                   ..........
     |--------|                                   |--------|
     | attr W |                                   | attr n |
     +--------+                                   +--------+

But that doesn't happen properly - the attribute tracking indexes
are not pointing to the right locations. What we end up with is both
the old attribute to be removed pointing at L4:0 and the new
attribute at L4:1.  On a debug kernel, this assert fails like so:

XFS: Assertion failed: args->index2 < be16_to_cpu(leaf2->hdr.count), file: fs/xfs/xfs_attr_leaf.c, line: 2725

because the new attribute location does not exist. On a production
kernel, this goes unnoticed and the code proceeds ahead merrily and
removes L4 because it thinks that is the block that is no longer
needed. This leaves the hash index node pointing to entries
L1, L4 and L2, but only blocks L1, L3 and L2 to exist. Further, the
leaf level sibling list is L1 <-> L4 <-> L2, but L4 is now free
space, and so everything is busted. This corruption is caused by the
removal of the old attribute triggering a join - it joins everything
correctly but then frees the wrong block.

xfs_repair will report something like:

bad sibling back pointer for block 4 in attribute fork for inode 131
problem with attribute contents in inode 131
would clear attr fork
bad nblocks 8 for inode 131, would reset to 3
bad anextents 4 for inode 131, would reset to 0

The problem lies in the assignment of the old/new blocks for
tracking purposes when the double leaf split occurs. The first split
tries to place the new attribute inside the current leaf (i.e.
"inleaf == true") and moves the old attribute (X) to the new block.
This sets up the old block/index to L1:X, and newly allocated
block to L3:0. It then moves attr X to the new block and tries to
insert attr Y at the old index. That fails, so it splits again.

With the second split, the rebalance ends up placing the new attr in
the second new block - L4:0 - and this is where the code goes wrong.
What is does is it sets both the new and old block index to the
second new block. Hence it inserts attr Y at the right place (L4:0)
but overwrites the current location of the attr to replace that is
held in the new block index (currently L3:0). It over writes it with
L4:1 - the index we later assert fail on.

Hopefully this table will show this in a foramt that is a bit easier
to understand:

Split		old attr index		new attr index
		vanilla	patched		vanilla	patched
before 1st	L1:26	L1:26		N/A	N/A
after 1st	L3:0	L3:0		L1:26	L1:26
after 2nd	L4:0	L3:0		L4:1	L4:0
                ^^^^			^^^^
		wrong			wrong

The fix is surprisingly simple, for all this analysis - just stop
the rebalance on the out-of leaf case from overwriting the new attr
index - it's already correct for the double split case.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      42e2976f
    • L
      Linux 3.7-rc6 · f4a75d2e
      由 Linus Torvalds 提交于
      f4a75d2e
    • L
      Merge git://git.kernel.org/pub/scm/virt/kvm/kvm · 51844b0f
      由 Linus Torvalds 提交于 
      Pull KVM fix from Marcelo Tosatti:
 "A correction for oops on module init with older Intel hosts."

* git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Fix invalid secondary exec controls in vmx_cpuid_update()
      51844b0f
    • L
      Merge branch 'akpm' (Fixes from Andrew) · 0cad3ff4
      由 Linus Torvalds 提交于 
      Merge misc fixes from Andrew Morton.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (12 patches)
  revert "mm: fix-up zone present pages"
  tmpfs: change final i_blocks BUG to WARNING
  tmpfs: fix shmem_getpage_gfp() VM_BUG_ON
  mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
  mm: revert "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures"
  rapidio: fix kernel-doc warnings
  swapfile: fix name leak in swapoff
  memcg: fix hotplugged memory zone oops
  mips, arc: fix build failure
  memcg: oom: fix totalpages calculation for memory.swappiness==0
  mm: fix build warning for uninitialized value
  mm: add anon_vma_lock to validate_mm()
      0cad3ff4
    • A
      revert "mm: fix-up zone present pages" · 5576646f
      由 Andrew Morton 提交于 
      Revert commit 7f1290f2 ("mm: fix-up zone present pages")

That patch tried to fix a issue when calculating zone->present_pages,
but it caused a regression on 32bit systems with HIGHMEM.  With that
change, reset_zone_present_pages() resets all zone->present_pages to
zero, and fixup_zone_present_pages() is called to recalculate
zone->present_pages when the boot allocator frees core memory pages into
buddy allocator.  Because highmem pages are not freed by bootmem
allocator, all highmem zones' present_pages becomes zero.

Various options for improving the situation are being discussed but for
now, let's return to the 3.6 code.

Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Tested-by: NChris Clayton <chris2553@googlemail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5576646f
    • H
      tmpfs: change final i_blocks BUG to WARNING · 0f3c42f5
      由 Hugh Dickins 提交于 
      Under a particular load on one machine, I have hit shmem_evict_inode()'s
BUG_ON(inode->i_blocks), enough times to narrow it down to a particular
race between swapout and eviction.

It comes from the "if (freed > 0)" asymmetry in shmem_recalc_inode(),
and the lack of coherent locking between mapping's nrpages and shmem's
swapped count.  There's a window in shmem_writepage(), between lowering
nrpages in shmem_delete_from_page_cache() and then raising swapped
count, when the freed count appears to be +1 when it should be 0, and
then the asymmetry stops it from being corrected with -1 before hitting
the BUG.

One answer is coherent locking: using tree_lock throughout, without
info->lock; reasonable, but the raw_spin_lock in percpu_counter_add() on
used_blocks makes that messier than expected.  Another answer may be a
further effort to eliminate the weird shmem_recalc_inode() altogether,
but previous attempts at that failed.

So far undecided, but for now change the BUG_ON to WARN_ON: in usual
circumstances it remains a useful consistency check.
Signed-off-by: NHugh 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>
      0f3c42f5