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  1. 28 Oct, 2006 3 commits
    • Martin Bligh's avatar
      [PATCH] Use min of two prio settings in calculating distress for reclaim · bbdb396a
      Martin Bligh authored 
      If try_to_free_pages / balance_pgdat are called with a gfp_mask specifying
GFP_IO and/or GFP_FS, they will reclaim the requisite number of pages, and the
reset prev_priority to DEF_PRIORITY (or to some other high (ie: unurgent)
value).

However, another reclaimer without those gfp_mask flags set (say, GFP_NOIO)
may still be struggling to reclaim pages.  The concurrent overwrite of
zone->prev_priority will cause this GFP_NOIO thread to unexpectedly cease
deactivating mapped pages, thus causing reclaim difficulties.

Fix this is to key the distress calculation not off zone->prev_priority, but
also take into account the local caller's priority by using
min(zone->prev_priority, sc->priority)
Signed-off-by: default avatarMartin J. Bligh <mbligh@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      bbdb396a
    • Martin Bligh's avatar
      [PATCH] vmscan: Fix temp_priority race · 3bb1a852
      Martin Bligh authored 
      The temp_priority field in zone is racy, as we can walk through a reclaim
path, and just before we copy it into prev_priority, it can be overwritten
(say with DEF_PRIORITY) by another reclaimer.

The same bug is contained in both try_to_free_pages and balance_pgdat, but
it is fixed slightly differently.  In balance_pgdat, we keep a separate
priority record per zone in a local array.  In try_to_free_pages there is
no need to do this, as the priority level is the same for all zones that we
reclaim from.

Impact of this bug is that temp_priority is copied into prev_priority, and
setting this artificially high causes reclaimers to set distress
artificially low.  They then fail to reclaim mapped pages, when they are,
in fact, under severe memory pressure (their priority may be as low as 0).
This causes the OOM killer to fire incorrectly.

From: Andrew Morton <akpm@osdl.org>

__zone_reclaim() isn't modifying zone->prev_priority.  But zone->prev_priority
is used in the decision whether or not to bring mapped pages onto the inactive
list.  Hence there's a risk here that __zone_reclaim() will fail because
zone->prev_priority ir large (ie: low urgency) and lots of mapped pages end up
stuck on the active list.

Fix that up by decreasing (ie making more urgent) zone->prev_priority as
__zone_reclaim() scans the zone's pages.

This bug perhaps explains why ZONE_RECLAIM_PRIORITY was created.  It should be
possible to remove that now, and to just start out at DEF_PRIORITY?

Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      3bb1a852
    • Nick Piggin's avatar
      [PATCH] mm: clean up pagecache allocation · 2ae88149
      Nick Piggin authored 
      - Consolidate page_cache_alloc

- Fix splice: only the pagecache pages and filesystem data need to use
  mapping_gfp_mask.

- Fix grab_cache_page_nowait: same as splice, also honour NUMA placement.
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2ae88149
  3. 27 Oct, 2006 11 commits
  5. 26 Oct, 2006 23 commits
  7. 25 Oct, 2006 3 commits
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