From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (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 A2498347531; Tue, 3 Mar 2026 21:12:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772572339; cv=none; b=f6r4CjglLtWKVJOy4JYUAvvA1d+1VDw59Q+D3IRlAArknb4OVWHvoKYoDBKh+si06TqgElg0iPH5nJ4GZXxfhvvWH+gPHWQ9kOBuu6p27QRtAENoOf2hwllBaaAbOT5NmUrvWdyE7CRXWxPRbYJ4wCoXGSisNMZklUUtUXUS/mc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772572339; c=relaxed/simple; bh=gZetZJNjR70T/LFjqoXtayWjEQgG9hfstgIaETdeEKA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=GVaUzASkMO56OeHFEBO4ORRXDDarI5LAfrqfuEcLjfO/HlTdKcMc1mtqOKIm37wzbxyThM91k39X59spQi/ZlhqLtRYk8Qy2wSlrZW9va35xtLSPIpdfvd0x/nJ+N6bxCVsxzh43uOsqs3yH5ISGNbL9bFnu0i2ukdJ14n+8Jus= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=H/VJE0Jl; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="H/VJE0Jl" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=gZetZJNjR70T/LFjqoXtayWjEQgG9hfstgIaETdeEKA=; t=1772572338; x=1773781938; b=H/VJE0JliLw2EDZe2ip9cZFmISiPygr1rsur4M9yJT/9Tsq n6drnklx45ap7WJ7DUDy+1fcPaudpFFiTHSxRDFTuq8P/jpODOVCZYRatZ+w/k2efuxMwh8sR3Axu U1fozS6cMkcAl0ykRo9gu2UNr0fjgso5sIB4VmVV9WKcFi+/WBKYMjvJ0iiZc7xMM+0sXTw4TbIl4 fWj+X4WY2syGvHf+neFzypg9A9mOsTR5Mrov6P8PRiQLz/2lSI8XRjq1Uh+pHizRYn9p8nBd72ZeY rGJvLc1kzuXp8WEdBYfU2xr0Cd54V/cnVx3rNJ6cZ9vwazNOsk6ZH3H9Ej/pSXPA==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1vxX2K-00000007KsF-3UfN; Tue, 03 Mar 2026 22:12:13 +0100 Message-ID: <3303d57a4ea6776dbc66ca72441023f76e6f1234.camel@sipsolutions.net> Subject: Re: 6.18.13 iwlwifi deadlock allocating cma while work-item is active. From: Johannes Berg To: Tejun Heo Cc: Ben Greear , linux-wireless , "Korenblit, Miriam Rachel" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Tue, 03 Mar 2026 22:12:12 +0100 In-Reply-To: References: <18c4bfed-caca-bef3-a139-63d7fa48940a@candelatech.com> <3456b2c89f057900b39ce79ea8ca1154c5014e43.camel@sipsolutions.net> <0de6c8d1-d2fa-44ac-8025-cfcfecd87b02@candelatech.com> <35779061f94c2a55bb58dcd619ae91c618509cf4.camel@sipsolutions.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-malware-bazaar: not-scanned On Tue, 2026-03-03 at 10:52 -1000, Tejun Heo wrote: > Hello, >=20 > On Tue, Mar 03, 2026 at 12:49:24PM +0100, Johannes Berg wrote: > > Fair. I don't know, I don't think there's anything that even shows that > > there's a dependency between the two workqueues and the > > "((wq_completion)events_unbound)" and "((wq_completion)events)", and > > there would have to be for it to deadlock this way because of that? > >=20 > > But one is mm_percpu_wq and the other is system_percpu_wq. > >=20 > > Tejun, does the workqueue code somehow introduce a dependency between > > different per-CPU workqueues that's not modelled in lockdep? >=20 > Hopefully not. Kinda late to the party. Why isn't mm_percpu_wq making > forward progress? That should in all circumstances. What's the work item = and > kworker doing? Oh and in addition: the worker that's kicked off by __lru_add_drain_all() doesn't really seem to do anything long-running? It's lru_add_drain_per_cpu(), which is lru_add_and_bh_lrus_drain(), which would appear to be entirely non-sleepable code (holding either local locks or having irqs disabled.) It also doesn't show up in the log, apparently, hence my question about strange dependencies. johannes