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>
(cherry picked from commit b4c5c60920e3b0c4598f43e7317559f6aec51531)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 1e14825..674b851 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -621,11 +621,18 @@
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,
@@ -665,8 +672,15 @@
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: