From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8FA723B52FF for ; Mon, 27 Apr 2026 10:58:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777287530; cv=none; b=E90gGnfHyKJiLTXnDBG6MOz6VpQFlntRd3u1AGvjSKPsL8oZuhkNWTPjOJdbWWfc05Zce8rR97X5oscMGzu8EtqNQnTi6XyS3pE+NuVDz3f67v/cnhhsggZDMBXc9TK2+QLYZZWaWmpPQWtEzAyiCKek72ouVLkD88cK6C9XQK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777287530; c=relaxed/simple; bh=ysEOka+TnGaRrctGVbUa7UgmVysNjZTzHeUX5nKhHfg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rUTjsar6tMv28xsBEWvFV+EWoyd2ML238N+DSx6FJKcmk3DZG40sNUnd2ENWfrl1hNlvjW6vHdSDa27yPak4deuIdwZ0A4U1Md/MCxp+NkgxajSCutVSoH/mtUVM48LdLs20AJUhLbWBAjqjWW1ya5UoDvYOdoR12pdIhaDY5/0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=sj91+h2F; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="sj91+h2F" Message-ID: <93cab3a3-1a67-4ac0-a818-f333d8017bc7@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1777287526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mC/SUXF6qmjl4I2YmUCpIFnBd715RpusDKL8gxRM2m8=; b=sj91+h2FCn6FNfkkxcVlMhdGDID905wb6k5PpVtes3BGCdCrQDPp/vXU+amHHWxaeF/Nak u8EDm/WFOVn3PvlJF6yeIYWeu8YT+q4Tm+g6N0lnrAc1xqRxnXkhl9hkMOhfvHF+qQGx/j syfIfRAlYok9/6+Cc8WoRf+2Iy+48Q4= Date: Mon, 27 Apr 2026 18:57:52 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [syzbot] [mm?] WARNING: bad unlock balance in do_wp_page To: Andrew Morton Cc: shakeel.butt@linux.dev, syzbot , Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, surenb@google.com, syzkaller-bugs@googlegroups.com, vbabka@kernel.org, Muchun Song References: <69edca15.170a0220.38e3f1.0000.GAE@google.com> <20260426034938.db29d74982a8eb8463f8cf3a@linux-foundation.org> <20260426105532.43768b24a42744f1b52fdff2@linux-foundation.org> <3591c663-a4a9-4c22-97cf-b58b2e7d8a41@linux.dev> <20260427034402.096cb95de92bec15becc78bb@linux-foundation.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <20260427034402.096cb95de92bec15becc78bb@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 4/27/26 6:44 PM, Andrew Morton wrote: > On Mon, 27 Apr 2026 17:43:38 +0800 Qi Zheng wrote: > >> >> Alright, it seems I have successfully reproduced it: >> (The reproducer is attached at the bottom of this email.) > > That's a lot of code. Thanks for doing that. Maybe there's something > here we can put into selftests/ If we are inclined to drop rebinding, then perhaps it's unnecessary to add selftest for it. ;) > >>>> >>>>> However, in a production environment, this is practically impossible. >>>> >>>> Can you expand on this? >>>> >>>> sysbot isn't a production environment ;) >>> >>> Rebinding only works when the hierarchy is completely empty. This is >>> generally not the case in a production environment (e.g. when systemd >>> is used). >>> >>> BTW, it seems rebinding is about to be deprecated: >>> >>> cgroup1_reconfigure >>> --> pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", >>>             task_tgid_nr(current), current->comm); >>> >>> Also, it appears the current memcg subsystem assumes that >>> cgroup_subsys_on_dfl(memory_cgrp_subsys) cannot be changed at runtime. >>> (Please correct me if I missed anything.) >>> >>> If we can get a reproducer, we can try the following fix, or simply drop >>> rebinding altogether? > > We'll want something which is applicable to 7.1-rcX please. Removal of > rebinding sounds like something we'd address in 7.2 or later. Got it. > >>> From 6ae41b91339625dd7bf0f819f775f26e78171a73 Mon Sep 17 00:00:00 2001 >>> From: Qi Zheng >>> Date: Mon, 27 Apr 2026 11:20:21 +0800 >>> Subject: [PATCH] mm: memcontrol: fix rcu unbalance in >>>  get_non_dying_memcg_end() >>> >>> Signed-off-by: Qi Zheng >>> --- >>>  mm/memcontrol.c | 30 ++++++++++++++++++++---------- >>>  1 file changed, 20 insertions(+), 10 deletions(-) >> >> With the above patch applied, the warnings are gone. >> >> If no one objects, I'll submit the formal fix. Or should we actually >> just remove rebinding instead? > > I suggest we just fix up current -rc please. OK, will do. Thanks, Qi >