Subject: + mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch added to -mm tree
To: hannes@xxxxxxxxxxx,aarcange@xxxxxxxxxx,bob.liu@xxxxxxxxxx,david@xxxxxxxxxxxxx,gthelen@xxxxxxxxxx,hch@xxxxxxxxxxxxx,hughd@xxxxxxxxxx,jack@xxxxxxx,klamm@xxxxxxxxxxxxxx,kosaki.motohiro@xxxxxxxxxxxxxx,metin@xxxxxxxxxxxxx,mgorman@xxxxxxx,minchan@xxxxxxxxxx,ozgun@xxxxxxxxxxxxx,peterz@xxxxxxxxxxxxx,riel@xxxxxxxxxx,rmallon@xxxxxxxxx,semenzato@xxxxxxxxxx,tj@xxxxxxxxxx,vbabka@xxxxxxx,walken@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 04 Feb 2014 15:14:44 -0800
The patch titled
Subject: mm: shmem: save one radix tree lookup when truncating swapped pages
has been added to the -mm tree. Its filename is
mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
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From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: shmem: save one radix tree lookup when truncating swapped pages
Page cache radix tree slots are usually stabilized by the page lock, but
shmem's swap cookies have no such thing. Because the overall truncation
loop is lockless, the swap entry is currently confirmed by a tree lookup
and then deleted by another tree lookup under the same tree lock region.
Use radix_tree_delete_item() instead, which does the verification and
deletion with only one lookup. This also allows removing the delete-only
special case from shmem_radix_tree_replace().
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Bob Liu <bob.liu@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Luigi Semenzato <semenzato@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Metin Doslu <metin@xxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Ozgun Erdogan <ozgun@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Roman Gushchin <klamm@xxxxxxxxxxxxxx>
Cc: Ryan Mallon <rmallon@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff -puN mm/shmem.c~mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages mm/shmem.c
--- a/mm/shmem.c~mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages
+++ a/mm/shmem.c
@@ -242,19 +242,17 @@ static int shmem_radix_tree_replace(stru
pgoff_t index, void *expected, void *replacement)
{
void **pslot;
- void *item = NULL;
+ void *item;
VM_BUG_ON(!expected);
+ VM_BUG_ON(!replacement);
pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
- if (pslot)
- item = radix_tree_deref_slot_protected(pslot,
- &mapping->tree_lock);
+ if (!pslot)
+ return -ENOENT;
+ item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
if (item != expected)
return -ENOENT;
- if (replacement)
- radix_tree_replace_slot(pslot, replacement);
- else
- radix_tree_delete(&mapping->page_tree, index);
+ radix_tree_replace_slot(pslot, replacement);
return 0;
}
@@ -386,14 +384,15 @@ export:
static int shmem_free_swap(struct address_space *mapping,
pgoff_t index, void *radswap)
{
- int error;
+ void *old;
spin_lock_irq(&mapping->tree_lock);
- error = shmem_radix_tree_replace(mapping, index, radswap, NULL);
+ old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
spin_unlock_irq(&mapping->tree_lock);
- if (!error)
- free_swap_and_cache(radix_to_swp_entry(radswap));
- return error;
+ if (old != radswap)
+ return -ENOENT;
+ free_swap_and_cache(radix_to_swp_entry(radswap));
+ return 0;
}
/*
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-vmscan-respect-numa-policy-mask-when-shrinking-slab-on-direct-reclaim.patch
mm-vmscan-move-call-to-shrink_slab-to-shrink_zones.patch
mm-vmscan-remove-shrink_control-arg-from-do_try_to_free_pages.patch
mm-vmstat-fix-up-zone-state-accounting.patch
fs-cachefiles-use-add_to_page_cache_lru.patch
lib-radix-tree-radix_tree_delete_item.patch
mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
mm-filemap-move-radix-tree-hole-searching-here.patch
mm-fs-prepare-for-non-page-entries-in-page-cache-radix-trees.patch
mm-fs-store-shadow-entries-in-page-cache.patch
mm-thrash-detection-based-file-cache-sizing.patch
lib-radix_tree-tree-node-interface.patch
mm-keep-page-cache-radix-tree-nodes-in-check.patch
linux-next.patch
debugging-keep-track-of-page-owners.patch
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