From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-11.sinamail.sina.com.cn (r3-11.sinamail.sina.com.cn [202.108.3.11]) (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 1DA1F2BE02D for ; Thu, 27 Aug 2026 23:46:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787874370; cv=none; b=Me9TGOAHivqrk9AvKZZQJqQAHMBufaVPRwND+c3f6Qz5VijpFenG6uzVTgUL1StOAh3eilCpzcAqBOBfMFZPK1cp5Ii/6RoBVCLdstYukyITMSLbrdcWnBODGxd0SSCi+dC+ttYaLHaMGQ03A86RV2cPGHY/WkiJx/kMT3jVDzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787874370; c=relaxed/simple; bh=3KX/Fugr/Yv5DcLb8arEf1+fCu2wAAMZ9/Xxitb4YgI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JZivHgYGOO32IX/JhvtIWQE8Jge3kvcUjVu5mZBFnG17RMdAN6nSlk3yzwP29T6QXz2jRq3pF97HHej/hEZYm2QLJI59IurUMW+AfG+3gRY+9fa+Jcen+QYDHaHTebvwC6KxAg93MFHmIymoFSW5BdNIl0GKzxoZ6NE83rTLKuE= 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=lGPbokFX; arc=none smtp.client-ip=202.108.3.11 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="lGPbokFX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1787874365; bh=CXmNRXpwDr9L+NRSTgprwbZvNbEWKioENjFRaHEwz88=; h=From:Subject:Date:Message-ID; b=lGPbokFX9whDKqfuSS5D9GXkPAjUSP3SNiLQxGO45d4M+H080O/R89raowZctauJK KGG7iojlSUc4C0l2mGa0v+mEWpZwf5VVoz0qSSBT9z6yiJxYsOaAES69NuNeCfOGDz nXHPhdWZ2sxbxwa3M786z365h9K8SxXKMTHyZRHc= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.194]) by sina.com (10.54.253.34) with ESMTP id 6A90CC3500000F0E; Thu, 28 Aug 2026 07:46:00 +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: 8115396292064 X-SMAIL-UIID: 0A5ADD4195004BCDB6DFE08C898C3124-20260828-074600-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [input?] possible deadlock in tasklet_action_common (2) Date: Fri, 28 Aug 2026 07:45:46 +0800 Message-ID: <20260827234547.1861-1-hdanton@sina.com> In-Reply-To: <6a655704.70955b6c.323240.0028.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: Sat, 25 Jul 2026 17:38:28 -0700 [thread overview] > syzbot has found a reproducer for the following issue on: > > HEAD commit: cc2b5f627e8c Add linux-next specific files for 20260714 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=13d446b9580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f > dashboard link: https://syzkaller.appspot.com/bug?extid=b5d7ab56d43de3fd5aac > compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1310a232580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13c3b2ea580000 #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd --- x/kernel/softirq.c +++ y/kernel/softirq.c @@ -956,7 +956,6 @@ static void tasklet_action_common(struct tl_head->tail = &tl_head->head; local_irq_enable(); - tasklet_lock_callback(); while (list) { struct tasklet_struct *t = list; @@ -976,7 +975,6 @@ static void tasklet_action_common(struct } } tasklet_unlock(t); - tasklet_callback_sync_wait_running(); continue; } tasklet_unlock(t); @@ -989,7 +987,6 @@ static void tasklet_action_common(struct __raise_softirq_irqoff(softirq_nr); local_irq_enable(); } - tasklet_unlock_callback(); } static __latent_entropy void tasklet_action(void) @@ -1042,7 +1039,7 @@ void tasklet_unlock_spin_wait(struct tas * interrupt processing or prevents ksoftirqd from * running. */ - tasklet_callback_cancel_wait_running(); + tasklet_unlock_wait(t); } else { cpu_relax(); } --