Patch "zram: revalidate disk under init_lock" has been added to the 4.9-stable tree

Patch "zram: revalidate disk under init_lock" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    zram: revalidate disk under init_lock

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     zram-revalidate-disk-under-init_lock.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e7ccfc4ccb703e0f033bd4617580039898e912dd Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Tue, 10 Jan 2017 16:58:18 -0800
Subject: zram: revalidate disk under init_lock

From: Minchan Kim <minchan@kernel.org>

commit e7ccfc4ccb703e0f033bd4617580039898e912dd upstream.

Commit b4c5c60920e3 ("zram: avoid lockdep splat by revalidate_disk")
moved revalidate_disk call out of init_lock to avoid lockdep
false-positive splat.  However, commit 08eee69fcf6b ("zram: remove
init_lock in zram_make_request") removed init_lock in IO path so there
is no worry about lockdep splat.  So, let's restore it.

This patch is needed to set BDI_CAP_STABLE_WRITES atomically in next
patch.

Fixes: da9556a2367c ("zram: user per-cpu compression streams")
Link: http://lkml.kernel.org/r/1482366980-3782-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Hyeoncheol Lee <cheol.lee@lge.com>
Cc: <yjay.kim@lge.com>
Cc: Sangseok Lee <sangseok.lee@lge.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/zram/zram_drv.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1094,14 +1094,8 @@ static ssize_t disksize_store(struct dev
 	zram->comp = comp;
 	zram->disksize = disksize;
 	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-	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);
+	up_write(&zram->init_lock);
 
 	return len;
 


Patches currently in stable-queue which might be from minchan@kernel.org are

queue-4.9/zram-support-bdi_cap_stable_writes.patch
queue-4.9/zram-revalidate-disk-under-init_lock.patch
queue-4.9/mm-pmd-dirty-emulation-in-page-fault-handler.patch