This is a note to let you know that I've just added the patch titled
debugobjects: Don't wake up kswapd from fill_pool()
to the 5.4-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:
debugobjects-don-t-wake-up-kswapd-from-fill_pool.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From eb799279fb1f9c63c520fe8c1c41cb9154252db6 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 11 May 2023 22:47:32 +0900
Subject: debugobjects: Don't wake up kswapd from fill_pool()
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
commit eb799279fb1f9c63c520fe8c1c41cb9154252db6 upstream.
syzbot is reporting a lockdep warning in fill_pool() because the allocation
from debugobjects is using GFP_ATOMIC, which is (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)
and therefore tries to wake up kswapd, which acquires kswapd_wait::lock.
Since fill_pool() might be called with arbitrary locks held, fill_pool()
should not assume that acquiring kswapd_wait::lock is safe.
Use __GFP_HIGH instead and remove __GFP_NORETRY as it is pointless for
!__GFP_DIRECT_RECLAIM allocation.
Fixes: 3ac7fe5a4aab ("infrastructure to debug (dynamic) objects")
Reported-by: syzbot <syzbot+fe0c72f0ccbb93786380@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/6577e1fa-b6ee-f2be-2414-a2b51b1c5e30@xxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=fe0c72f0ccbb93786380
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/debugobjects.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -128,7 +128,7 @@ static const char *obj_states[ODEBUG_STA
static void fill_pool(void)
{
- gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
+ gfp_t gfp = __GFP_HIGH | __GFP_NOWARN;
struct debug_obj *obj;
unsigned long flags;
Patches currently in stable-queue which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
queue-5.4/fs-hfsplus-remove-warn_on-from-hfsplus_cat_-read-wri.patch
queue-5.4/debugobjects-don-t-wake-up-kswapd-from-fill_pool.patch
