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| author | Vitaly Wool <vitalywool@gmail.com> | 2018-04-05 16:23:32 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-05 21:36:25 -0700 |
| commit | 5c9bab592f53328b3e00d7293378b714abf47a2a (patch) | |
| tree | 8785d51da7ca697c8a781e56d309f341e3bb13a3 | |
| parent | 605ca5ede7643a01f4c4a15913f9714ac297f8a6 (diff) | |
| download | linux-stable-5c9bab592f53328b3e00d7293378b714abf47a2a.tar.gz linux-stable-5c9bab592f53328b3e00d7293378b714abf47a2a.tar.bz2 linux-stable-5c9bab592f53328b3e00d7293378b714abf47a2a.zip | |
z3fold: limit use of stale list for allocation
Currently if z3fold couldn't find an unbuddied page it would first try
to pull a page off the stale list. The problem with this approach is
that we can't 100% guarantee that the page is not processed by the
workqueue thread at the same time unless we run cancel_work_sync() on
it, which we can't do if we're in an atomic context. So let's just
limit stale list usage to non-atomic contexts only.
Link: http://lkml.kernel.org/r/47ab51e7-e9c1-d30e-ab17-f734dbc3abce@gmail.com
Signed-off-by: Vitaly Vul <vitaly.vul@sony.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <Oleksiy.Avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/z3fold.c | 35 |
1 files changed, 19 insertions, 16 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index d589d318727f..f579ad4a8100 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -620,24 +620,27 @@ lookup: bud = FIRST; } - spin_lock(&pool->stale_lock); - zhdr = list_first_entry_or_null(&pool->stale, - struct z3fold_header, buddy); - /* - * Before allocating a page, let's see if we can take one from the - * stale pages list. cancel_work_sync() can sleep so we must make - * sure it won't be called in case we're in atomic context. - */ - if (zhdr && (can_sleep || !work_pending(&zhdr->work))) { - list_del(&zhdr->buddy); - spin_unlock(&pool->stale_lock); - if (can_sleep) + page = NULL; + if (can_sleep) { + spin_lock(&pool->stale_lock); + zhdr = list_first_entry_or_null(&pool->stale, + struct z3fold_header, buddy); + /* + * Before allocating a page, let's see if we can take one from + * the stale pages list. cancel_work_sync() can sleep so we + * limit this case to the contexts where we can sleep + */ + if (zhdr) { + list_del(&zhdr->buddy); + spin_unlock(&pool->stale_lock); cancel_work_sync(&zhdr->work); - page = virt_to_page(zhdr); - } else { - spin_unlock(&pool->stale_lock); - page = alloc_page(gfp); + page = virt_to_page(zhdr); + } else { + spin_unlock(&pool->stale_lock); + } } + if (!page) + page = alloc_page(gfp); if (!page) return -ENOMEM; |