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[PATCH] shrink_list(): skip anon pages if not may_swap 

Martin Hicks' page cache reclaim patch added the 'may_swap' flag to the
scan_control struct; and modified shrink_list() not to add anon pages to
the swap cache if may_swap is not asserted.

Ref:  http://marc.theaimsgroup.com/?l=linux-mm&m=111461480725322&w=4

However, further down, if the page is mapped, shrink_list() calls
try_to_unmap() which will call try_to_unmap_one() via try_to_unmap_anon ().
 try_to_unmap_one() will BUG_ON() an anon page that is NOT in the swap
cache.  Martin says he never encountered this path in his testing, but
agrees that it might happen.

This patch modifies shrink_list() to skip anon pages that are not already
in the swap cache when !may_swap, rather than just not adding them to the
cache.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
hifive-unleashed-5.1
Lee Schermerhorn 2005-10-29 18:15:51 -07:00 committed by Linus Torvalds
parent b57b98d147
commit c340010e4b
1 changed files with 3 additions and 1 deletions
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4
mm/vmscan.c
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@ -417,7 +417,9 @@ static int shrink_list(struct list_head *page_list, struct scan_control *sc)
* Anonymous process memory has backing store?
* Try to allocate it some swap space here.
*/
if (PageAnon(page) && !PageSwapCache(page) && sc->may_swap) {
if (PageAnon(page) && !PageSwapCache(page)) {
if (!sc->may_swap)
goto keep_locked;
if (!add_to_swap(page))
goto activate_locked;
}