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UPSTREAM: zram: avoid lockdep splat by revalidate_disk 

(cherry-pick from commit b4c5c60920e3b0c4598f43e7317559f6aec51531)

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").

Bug: 25951511

Change-Id: Id4498d2993849b57bf37b2fa17470c39e8837b58
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>
This commit is contained in:
Minchan Kim 2014-07-23 14:00:04 -07:00 committed by Srinivasarao P
parent 009c1328a9
commit e8eb4ffa79
1 changed files with 18 additions and 4 deletions
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22
drivers/block/zram/zram_drv.c
View File

@ -700,11 +700,18 @@ 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,
@ -744,8 +751,15 @@ 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: