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  1. 15 2月, 2008 5 次提交
  3. 09 2月, 2008 8 次提交
  5. 06 2月, 2008 4 次提交
    • A
      Fix /proc dcache deadlock in do_exit · 7766755a
      由 Andrea Arcangeli 提交于 
      This patch fixes a sles9 system hang in start_this_handle from a customer
with some heavy workload where all tasks are waiting on kjournald to commit
the transaction, but kjournald waits on t_updates to go down to zero (it
never does).

This was reported as a lowmem shortage deadlock but when checking the debug
data I noticed the VM wasn't under pressure at all (well it was really
under vm pressure, because lots of tasks hanged in the VM prune_dcache
methods trying to flush dirty inodes, but no task was hanging in GFP_NOFS
mode, the holder of the journal handle should have if this was a vm issue
in the first place).

No task was apparently holding the leftover handle in the committing
transaction, so I deduced t_updates was stuck to 1 because a journal_stop
was never run by some path (this turned out to be correct).  With a debug
patch adding proper reverse links and stack trace logging in ext3 deployed
in production, I found journal_stop is never run because
mark_inode_dirty_sync is called inside release_task called by do_exit.
(that was quite fun because I would have never thought about this
subtleness, I thought a regular path in ext3 had a bug and it forgot to
call journal_stop)

do_exit->release_task->mark_inode_dirty_sync->schedule() (will never
come back to run journal_stop)

The reason is that shrink_dcache_parent is racy by design (feature not
a bug) and it can do blocking I/O in some case, but the point is that
calling shrink_dcache_parent at the last stage of do_exit isn't safe
for self-reaping tasks.

I guess the memory pressure of the unbalanced highmem system allowed
to trigger this more easily.

Now mainline doesn't have this line in iput (like sles9 has):

    	     if (inode->i_state & I_DIRTY_DELAYED)
	     			mark_inode_dirty_sync(inode);

so it will probably not crash with ext3, but for example ext2 implements an
I/O-blocking ext2_put_inode that will lead to similar screwups with
ext2_free_blocks never coming back and it's definitely wrong to call
blocking-IO paths inside do_exit.  So this should fix a subtle bug in
mainline too (not verified in practice though).  The equivalent fix for
ext3 is also not verified yet to fix the problem in sles9 but I don't have
doubt it will (it usually takes days to crash, so it'll take weeks to be
sure).

An alternate fix would be to offload that work to a kernel thread, but I
don't think a reschedule for this is worth it, the vm should be able to
collect those entries for the synchronous release_task.
Signed-off-by: NAndrea Arcangeli <andrea@suse.de>
Cc: Jan Kara <jack@ucw.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7766755a
    • M
      maps4: make page monitoring /proc file optional · 1e883281
      由 Matt Mackall 提交于 
      Make /proc/ page monitoring configurable

This puts the following files under an embedded config option:

/proc/pid/clear_refs
/proc/pid/smaps
/proc/pid/pagemap
/proc/kpagecount
/proc/kpageflags

[akpm@linux-foundation.org: Kconfig fix]
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1e883281
    • M
      maps4: add /proc/pid/pagemap interface · 85863e47
      由 Matt Mackall 提交于 
      This interface provides a mapping for each page in an address space to its
physical page frame number, allowing precise determination of what pages are
mapped and what pages are shared between processes.

New in this version:

- headers gone again (as recommended by Dave Hansen and Alan Cox)
- 64-bit entries (as per discussion with Andi Kleen)
- swap pte information exported (from Dave Hansen)
- page walker callback for holes (from Dave Hansen)
- direct put_user I/O (as suggested by Rusty Russell)

This patch folds in cleanups and swap PTE support from Dave Hansen
<haveblue@us.ibm.com>.
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      85863e47
    • M
      maps4: move clear_refs code to task_mmu.c · f248dcb3
      由 Matt Mackall 提交于 
      This puts all the clear_refs code where it belongs and probably lets things
compile on MMU-less systems as well.
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f248dcb3
  7. 02 2月, 2008 1 次提交
  9. 26 1月, 2008 1 次提交
  11. 03 1月, 2008 1 次提交
  13. 07 12月, 2007 1 次提交
  15. 30 11月, 2007 1 次提交
  17. 15 11月, 2007 1 次提交
  19. 23 10月, 2007 1 次提交
  21. 20 10月, 2007 11 次提交
  23. 17 10月, 2007 3 次提交
  25. 15 10月, 2007 1 次提交
  27. 01 8月, 2007 1 次提交