Patch "debugobjects: Don't wake up kswapd from fill_pool()" has been added to the 6.1-stable tree

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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 6.1-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-6.1 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
@@ -126,7 +126,7 @@ 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-6.1/debugobjects-don-t-wake-up-kswapd-from-fill_pool.patch



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