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| author | Minchan Kim <minchan@kernel.org> | 2014-07-23 23:00:04 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-24 00:10:54 +0200 |
| commit | b4c5c60920e3b0c4598f43e7317559f6aec51531 (patch) | |
| tree | 558613a15eb002c5a0aef4f77c99efc741cd5b4f /drivers/block/zram | |
| parent | mm/rmap.c: fix pgoff calculation to handle hugepage correctly (diff) | |
| download | linux-b4c5c60920e3b0c4598f43e7317559f6aec51531.tar.xz linux-b4c5c60920e3b0c4598f43e7317559f6aec51531.zip | |
zram: avoid lockdep splat by revalidate_disk
Sasha reported lockdep warning [1] introduced by [2].
It could be fixed by doing disk revalidation out of the init_lock. It's
okay because disk capacity change is protected by init_lock so that
revalidate_disk always sees up-to-date value so there is no race.
[1] https://lkml.org/lkml/2014/7/3/735
[2] zram: revalidate disk after capacity change
Fixes 2e32baea46ce ("zram: revalidate disk after capacity change").
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: "Alexander E. Patrakov" <patrakov@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/zram')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 089e72cd37be..36e54be402df 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -622,11 +622,18 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) memset(&zram->stats, 0, sizeof(zram->stats)); zram->disksize = 0; - if (reset_capacity) { + if (reset_capacity) set_capacity(zram->disk, 0); - revalidate_disk(zram->disk); - } + up_write(&zram->init_lock); + + /* + * Revalidate disk out of the init_lock to avoid lockdep splat. + * It's okay because disk's capacity is protected by init_lock + * so that revalidate_disk always sees up-to-date capacity. + */ + if (reset_capacity) + revalidate_disk(zram->disk); } static ssize_t disksize_store(struct device *dev, @@ -666,8 +673,15 @@ static ssize_t disksize_store(struct device *dev, zram->comp = comp; zram->disksize = disksize; set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); - revalidate_disk(zram->disk); up_write(&zram->init_lock); + + /* + * Revalidate disk out of the init_lock to avoid lockdep splat. + * It's okay because disk's capacity is protected by init_lock + * so that revalidate_disk always sees up-to-date capacity. + */ + revalidate_disk(zram->disk); + return len; out_destroy_comp: |