+ zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

+ zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: zram: fix uninitialized ZRAM not releasing backing device
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     zram-fix-uninitialized-zram-not-releasing-backing-device.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-fix-uninitialized-zram-not-releasing-backing-device.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: zram: fix uninitialized ZRAM not releasing backing device
Date: Tue, 10 Dec 2024 00:57:16 +0800

Setting backing device is done before ZRAM initialization.  If we set the
backing device, then remove the ZRAM module without initializing the
device, the backing device reference will be leaked and the device will be
hold forever.

Fix this by always reset the ZRAM fully on rmmod or reset store.

Link: https://lkml.kernel.org/r/20241209165717.94215-3-ryncsn@gmail.com
Fixes: 013bf95a83ec ("zram: add interface to specif backing device")
Signed-off-by: Kairui Song <kasong@tencent.com>
Reported-by: Desheng Wu <deshengwu@tencent.com>
Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-fix-uninitialized-zram-not-releasing-backing-device
+++ a/drivers/block/zram/zram_drv.c
@@ -1444,12 +1444,16 @@ static void zram_meta_free(struct zram *
 	size_t num_pages = disksize >> PAGE_SHIFT;
 	size_t index;
 
+	if (!zram->table)
+		return;
+
 	/* Free all pages that are still in this zram device */
 	for (index = 0; index < num_pages; index++)
 		zram_free_page(zram, index);
 
 	zs_destroy_pool(zram->mem_pool);
 	vfree(zram->table);
+	zram->table = NULL;
 }
 
 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
@@ -2334,11 +2338,6 @@ static void zram_reset_device(struct zra
 
 	zram->limit_pages = 0;
 
-	if (!init_done(zram)) {
-		up_write(&zram->init_lock);
-		return;
-	}
-
 	set_capacity_and_notify(zram->disk, 0);
 	part_stat_set_all(zram->disk->part0, 0);
 
_

Patches currently in -mm which might be from kasong@tencent.com are

zram-refuse-to-use-zero-sized-block-device-as-backing-device.patch
zram-fix-uninitialized-zram-not-releasing-backing-device.patch

Re: + zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

[Sergey Senozhatsky]

On (24/12/09 17:57), Andrew Morton wrote:
> Setting backing device is done before ZRAM initialization.  If we set the
> backing device, then remove the ZRAM module without initializing the
> device, the backing device reference will be leaked and the device will be
> hold forever.
> 
> Fix this by always reset the ZRAM fully on rmmod or reset store.
> 
> Link: https://lkml.kernel.org/r/20241209165717.94215-3-ryncsn@gmail.com
> Fixes: 013bf95a83ec ("zram: add interface to specif backing device")
> Signed-off-by: Kairui Song <kasong@tencent.com>
> Reported-by: Desheng Wu <deshengwu@tencent.com>
> Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>


Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>


A side note:
I'm not sure if this and zram-refuse-to-use-zero-sized-block-device-as-backing-device.patch
are worth the stable tag, they don't really fix problems that people run
into en masse.

Re: + zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

On Tue, 10 Dec 2024 13:08:15 +0900 Sergey Senozhatsky <senozhatsky@chromium.org> wrote:

> I'm not sure if this and zram-refuse-to-use-zero-sized-block-device-as-backing-device.patch
> are worth the stable tag, they don't really fix problems that people run
> into en masse.

Me either, but they're very simple patches.

Re: + zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

[Sergey Senozhatsky]

On (24/12/09 21:20), Andrew Morton wrote:
> On Tue, 10 Dec 2024 13:08:15 +0900 Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
> 
> > I'm not sure if this and zram-refuse-to-use-zero-sized-block-device-as-backing-device.patch
> > are worth the stable tag, they don't really fix problems that people run
> > into en masse.
> 
> Me either, but they're very simple patches.

Fair enough.

+ zram-fix-uninitialized-zram-not-releasing-backing-device.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: zram: fix uninitialized ZRAM not releasing backing device
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     zram-fix-uninitialized-zram-not-releasing-backing-device.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-fix-uninitialized-zram-not-releasing-backing-device.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Kairui Song <kasong@tencent.com>
Subject: zram: fix uninitialized ZRAM not releasing backing device
Date: Thu, 5 Dec 2024 02:02:24 +0800

Setting backing device is done before ZRAM initialization.  If we set the
backing device, then remove the ZRAM module without initializing the
device, the backing device reference will be leaked and the device will be
hold forever.

Fix this by always check and release the backing device when resetting or
removing ZRAM.

Link: https://lkml.kernel.org/r/20241204180224.31069-3-ryncsn@gmail.com
Fixes: 013bf95a83ec ("zram: add interface to specif backing device")
Signed-off-by: Kairui Song <kasong@tencent.com>
Reported-by: Desheng Wu <deshengwu@tencent.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/block/zram/zram_drv.c~zram-fix-uninitialized-zram-not-releasing-backing-device
+++ a/drivers/block/zram/zram_drv.c
@@ -2335,6 +2335,9 @@ static void zram_reset_device(struct zra
 	zram->limit_pages = 0;
 
 	if (!init_done(zram)) {
+		/* Backing device could be set before ZRAM initialization. */
+		reset_bdev(zram);
+
 		up_write(&zram->init_lock);
 		return;
 	}
_

Patches currently in -mm which might be from kasong@tencent.com are

zram-refuse-to-use-zero-sized-block-device-as-backing-device.patch
zram-fix-uninitialized-zram-not-releasing-backing-device.patch