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Groups > linux.kernel > #1309783
| From | Junil Lee <junil0814.lee@lge.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition |
| Date | 2016-01-15 01:40 +0100 |
| Message-ID | <qR0AN-6Cy-9@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
To prevent unlock at the not correct situation, tagging the new obj to assure lock in migrate_zspage() before right unlock path. Two functions are in race condition by tag which set 1 on last bit of obj, however unlock succrently when update new obj to handle before call unpin_tag() which is right unlock path. summarize this problem by call flow as below: CPU0 CPU1 migrate_zspage find_alloced_obj() trypin_tag() -- obj |= HANDLE_PIN_BIT obj_malloc() -- new obj is not set zs_free record_obj() -- unlock and break sync pin_tag() -- get lock unpin_tag() Signed-off-by: Junil Lee <junil0814.lee@lge.com> --- mm/zsmalloc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index e7414ce..bb459ef 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1635,6 +1635,7 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class, free_obj = obj_malloc(d_page, class, handle); zs_object_copy(free_obj, used_obj, class); index++; + free_obj |= BIT(HANDLE_PIN_BIT); record_obj(handle, free_obj); unpin_tag(handle); obj_free(pool, class, used_obj); -- 2.6.2
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[PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Junil Lee <junil0814.lee@lge.com> - 2016-01-15 01:40 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-15 03:40 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-15 04:30 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-15 04:30 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-15 05:50 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-15 06:10 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-20 08:00 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Russell Knize <rknize@motorola.com> - 2016-01-20 16:30 +0100
Re: [PATCH] zsmalloc: fix migrate_zspage-zs_free race condition Minchan Kim <minchan@kernel.org> - 2016-01-15 06:10 +0100
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