From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-165.sina.com.cn (smtp153-165.sina.com.cn [61.135.153.165]) (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 62B4D1DE4FB for ; Wed, 8 Oct 2025 01:10:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.165 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759885851; cv=none; b=dFi7n3DU60jfKPD+i9kREAVTCHNi1wCbOKMTbHj3JsfgfC8NmeA5ib31UGFFJpsdlGWzo5WDlPSPAK+X+Bbs6FbgRzPXpEKc0gq9wA/29nrzfzQ9x1K5IvPoy2woihapu7B95Jmz4/fWkFrhlmpvY6gaPjyfJwyZAIonWx9m1iY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759885851; c=relaxed/simple; bh=whGDHiCRfNS7j5DWDDgdMwTjwwfI6IJun0sN9QVlHaM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LWkrphrxY4r1yd92qGcOd2JoDz93TErMkQeKx0zb/qpLL5R4vdSmbAPsKnK2WnURcBkOHEJxJXgl6DbkQUynG3jn8YNoh1mwjPv41HbAeM4p3L6ykjTN+OKlzqhztfbcmanmxHNOgFsO8u9x2mi0mgxiH1eLK5HOv2yGLjcEEdM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=r+Kuc63Y; arc=none smtp.client-ip=61.135.153.165 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="r+Kuc63Y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1759885842; bh=jCebY8UK4SHidkoM7FSA/sJzpS1AI0S6Bypqpp6wEsE=; h=From:Subject:Date:Message-ID; b=r+Kuc63YMQJmQ7MlGzJIbwR7RpN82Bs1pt8dDk5wf6IunIYwqNBw+IruJ7Je9xcfA m3+eBvoy4seEdEH7L3dzmTRjKHoBV4rNgy9Ua5teB/5smvpxc9E08tyzDkyhWJUGYc poCtlZCuWQj0rJLaMlqfT58SFenq1+XHayW9Xfv4= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.58.236]) by sina.com (10.54.253.32) with ESMTP id 68E5BA070000733E; Wed, 8 Oct 2025 09:10:32 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 9110464457053 X-SMAIL-UIID: A59A077D66C24934AA0D36DD0E91EBA3-20251008-091032-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [fuse?] possible deadlock in __folio_end_writeback Date: Wed, 8 Oct 2025 09:10:20 +0800 Message-ID: <20251008011021.8322-1-hdanton@sina.com> In-Reply-To: <68e583e1.a00a0220.298cc0.0485.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Tue, 07 Oct 2025 14:19:29 -0700 [thread overview] > Hello, > > syzbot found the following issue on: > > HEAD commit: cbf33b8e0b36 Merge tag 'bpf-fixes' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17a25ee2580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=1b4263e12240e6e1 > dashboard link: https://syzkaller.appspot.com/bug?extid=27727256237e6bdd3649 > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14eaea7c580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=134c4304580000 #syz test --- x/lib/flex_proportions.c +++ y/lib/flex_proportions.c @@ -64,12 +64,14 @@ void fprop_global_destroy(struct fprop_g bool fprop_new_period(struct fprop_global *p, int periods) { s64 events = percpu_counter_sum(&p->events); + unsigned long flags; /* * Don't do anything if there are no events. */ if (events <= 1) return false; + local_irq_save(flags); preempt_disable_nested(); write_seqcount_begin(&p->sequence); if (periods < 64) @@ -79,6 +81,7 @@ bool fprop_new_period(struct fprop_globa p->period += periods; write_seqcount_end(&p->sequence); preempt_enable_nested(); + local_irq_restore(flags); return true; } --