From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 C9160329E5A for ; Fri, 27 Mar 2026 16:43:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774629838; cv=none; b=IaXBerABvKmoJfvBMFmBHVCCIbp6G9n0udjlhTqxmdi+3M248AHy9bsZVT7G3lKHmwbdUlHZigyJROa7EgDApmarnhRqT5/UHGYyQF1YKWk9O2wr9dd143RlqNHjLP7JIOoXgdCZUY1TM7VPLjT4ciV7X+Gmj5iyk/tPnzuRsbU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774629838; c=relaxed/simple; bh=r3HffDUcSTK4SgHjtBh63S6h8HAmfjKVUqUsHFgIsWU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=C0Jc5L8Ta2j4v6gGeQ3EFEyHfA1l4m+y9uSiNQMd1xqq3AoqcNKfilsQPnTIr12HatJxKEEtC1vxugmvxfNjP2pWnDufS8ousQdZcMO3Bg18eVofVOzEe4lgq+u3PMvDDkj4+x4F4crzafOyh9P9ZfHph/JId8RBdbQP01T6YXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=K7RNr0jB; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="K7RNr0jB" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=BINe5VahrxEruN6rxwODM4u4HsY0IVSQhq1Wvv0EbGk=; b=K7RNr0jBHMBreSkUMC6GHsQ8xq oj2iL/08cw+kAmOBPchjcuwG9elTEsrg+leMiYYGGbG0gOlKfiS/sfvctQ2ti0tk4mmou3PgpXwZ4 WoFQiKKhLqK7lJhFqYeCO27jaFRdKsjLJ0tgntyjx/UcMU9i4pN30WppvJSKn505TJJc8ymPVphxY 7bRzXLuNWA0U2B5L3YHrn5j0JD6MqRskdTgiqufutlq7USF/rPaV4Jd/NdvhecsJnysxzMaMj4+kQ aY2HZT6vPMNrYxXGEJaE5MZEtYrV2oyNbeJZENpwcmfAy6yYfKzU0GVh4Ff/2+tDIoF8iXuST5cs8 jfsIOuOg==; Received: from 2001-1c00-8d85-4b00-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:4b00:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1w6AHq-000000026WF-1d7E; Fri, 27 Mar 2026 16:43:54 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id DC218300E56; Fri, 27 Mar 2026 17:43:53 +0100 (CET) Date: Fri, 27 Mar 2026 17:43:53 +0100 From: Peter Zijlstra To: "Borah, Chaitanya Kumar" Cc: willy@infradead.org, linux-kernel@vger.kernel.org, "intel-gfx@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" , "Kurmi, Suresh Kumar" , "Saarinen, Jani" , ravitejax.veesam@intel.com Subject: Re: Regression on linux-next (next-20260324 ) Message-ID: <20260327164353.GM3739106@noisy.programming.kicks-ass.net> References: <20260327163100.GL3738010@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260327163100.GL3738010@noisy.programming.kicks-ass.net> On Fri, Mar 27, 2026 at 05:31:00PM +0100, Peter Zijlstra wrote: > On Fri, Mar 27, 2026 at 07:09:26PM +0530, Borah, Chaitanya Kumar wrote: > > Hello Matthew, > > > > Hope you are doing well. I am Chaitanya from the linux graphics team in > > Intel. > > > > This mail is regarding a regression we are seeing in our CI runs[1] on > > linux-next repository. > > > > Since the version next-20260324 [2], we are seeing the following regression > > > > ````````````````````````````````````````````````````````````````````````````````` > > <5>[ 157.361977] [IGT] Inactivity timeout exceeded. Killing the current > > test with SIGQUIT. > > <6>[ 157.362097] sysrq: HELP : loglevel(0-9) reboot(b) crash(c) > > show-all-locks(d) terminate-all-tasks(e) memory-full-oom-kill(f) > > kill-all-tasks(i) thaw-filesystems(j) sak(k) > > show-backtrace-all-active-cpus(l) show-memory-usage(m) nice-all-RT-tasks(n) > > poweroff(o) show-registers(p) show-all-timers(q) unraw(r) sync(s) > > show-task-states(t) unmount(u) force-fb(v) show-blocked-tasks(w) > > dump-ftrace-buffer(z) replay-kernel-logs(R) > > <6>[ 157.399543] sysrq: Show State > > <6>[ 157.403061] task:systemd state:S stack:0 pid:1 tgid:1 > > ppid:0 task_flags:0x400100 flags:0x00080000 > > <6>[ 157.403067] Call Trace: > > <6>[ 157.403069] > > <6>[ 157.403072] __schedule+0x5d7/0x1ef0 > > <6>[ 157.403078] ? lock_acquire+0xc4/0x300 > > <6>[ 157.403084] ? schedule+0x10e/0x180 > > <6>[ 157.403087] ? lock_release+0xcd/0x2b0 > > <6>[ 157.403092] schedule+0x3a/0x180 > > <6>[ 157.403094] schedule_hrtimeout_range_clock+0x112/0x120 > > <6>[ 157.403097] ? do_epoll_wait+0x3e4/0x5b0 > > <6>[ 157.403102] ? lock_release+0xcd/0x2b0 > > <6>[ 157.403104] ? _raw_spin_unlock_irq+0x27/0x70 > > <6>[ 157.403106] ? do_epoll_wait+0x3e4/0x5b0 > > <6>[ 157.403110] schedule_hrtimeout_range+0x13/0x30 > > ````````````````````````````````````````````````````````````````````````````````` > > Details log can be found in [3]. > > > > After bisecting the tree, the following patch [4] seems to be the first > > "bad" commit > > > > ````````````````````````````````````````````````````````````````````````````````````````````````````````` > > commit 25500ba7e77ce9d3d9b5a1929d41a2ee2e23f6fe > > Author: Matthew Wilcox (Oracle) willy@infradead.org > > Date:   Thu Mar 5 19:55:43 2026 +0000 > > > >     locking/mutex: Remove the list_head from struct mutex > > ````````````````````````````````````````````````````````````````````````````````````````````````````````` > > > > We could not revert the patch because of merge conflict but resetting to the > > parent of the commit seems to fix the issue. > > > > Could you please check why the patch causes this regression and provide a > > fix if necessary? > > Does this help? More tidy version of the same... --- diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h index b1834ab7e782..bb8b410779d4 100644 --- a/kernel/locking/ww_mutex.h +++ b/kernel/locking/ww_mutex.h @@ -42,7 +42,7 @@ __ww_waiter_last(struct mutex *lock) struct mutex_waiter *w = lock->first_waiter; if (w) - w = list_prev_entry(w, list); + w = __ww_waiter_prev(lock, w); return w; }