From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9EA4A606A33A for ; Wed, 4 Nov 2026 14:32:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=TcOpgZef Received: by kanga.kvack.org (Postfix) id BC1C86B05B4; Wed, 4 Nov 2026 09:32:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B72F36B05B5; Wed, 4 Nov 2026 09:32:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A62616B05B6; Wed, 4 Nov 2026 09:32:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 7E5F96B05B4 for ; Wed, 4 Nov 2026 09:32:12 -0500 (EST) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 1C9E014073E for ; Wed, 4 Nov 2026 14:32:12 +0000 (UTC) X-FDA: 85397676504.06.DF8DDC9 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf28.hostedemail.com (Postfix) with ESMTP id 70370C0003 for ; Wed, 4 Nov 2026 14:32:10 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TcOpgZef; spf=pass (imf28.hostedemail.com: domain of pratyush@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793802730; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ensURHApHSqZx6uOyzhFmn+kTScsXcNRPyYQC1uz1CU=; b=iXDVttxcX7M7SIb9pnA3f0xppO6zOlI1RNrSVseJ8XbV/suYD2vj3XIQUxfCVB+3oK0yjm zZ2Wq+gycM2h9s6gxqaYfBBrioVMTOXWKruuxltyleTx5UYhwe8h2n5T0rt38Jcf4iclcz 2Efb+RiwNImO2eeQOLUCiSd8rWA8S1U= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793802730; b=4c77aZwRupSwPTHHX8Z7P7Z9Oa+ABDkQDztK59vbxsl/toqMDpqTN6/cNNAlUpZxcco3kF ZFmvQy4wth6zWD711eW5lQD8Wq0PsUina9KFxCVl5tvoI5uOaJ5Hmd+mQVsPe+XjnIN9LR VHIf2uutMb5JFaSaPZiv9LlzayQp7hA= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=TcOpgZef; spf=pass (imf28.hostedemail.com: domain of pratyush@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 6032E6022E; Wed, 4 Nov 2026 14:32:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 753631F000C1; Wed, 4 Nov 2026 14:32:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793802729; bh=ensURHApHSqZx6uOyzhFmn+kTScsXcNRPyYQC1uz1CU=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=TcOpgZefoJQDj0LMKZN2iBGkvhXFOXPKKWcv/EELG3wUHGxyUFmCRM1ItUL21vHPU NL30EdFERhZSC/XY5znlGdQMZm3hLLB8tDKOgM7sntuTcodKpH25Nl4e8MahputugX iGMxROzfrdCI5MWnXSfHTdb6BnKnjgcxrpA7aF11iws3kFyfpO2J9N2x0jW5LvDTHw 1Las9U1zCRWFyJBh+l9Tz6tJ6e3xFAroBm5WNtxAiFB2PQC4jsJo5mfffKhohxhdco VgFwwZhMbiGRqPCJ/D1rhtDZiR9/MTBL0jU1idXwszX9SprqNES9MFPDmEX9CyJneA hXNHIUwLK6FZw== From: Pratyush Yadav To: David Matlack Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Alexander Graf , Andrew Morton , Baolin Wang , Christian Brauner , David Hildenbrand , Hugh Dickins , Jonathan Corbet , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Randy Dunlap , Samiullah Khawaja , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka Subject: Re: [PATCH v3 05/10] liveupdate: Don't WARN if tracking a retrieved file fails In-Reply-To: <20261103010216.3447716-6-dmatlack@google.com> (David Matlack's message of "Tue, 3 Nov 2026 01:02:11 +0000") References: <20261103010216.3447716-1-dmatlack@google.com> <20261103010216.3447716-6-dmatlack@google.com> Date: Wed, 04 Nov 2026 15:32:04 +0100 Message-ID: <2vxzmrrok6qj.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: eatcjahg8tnzrcracxrtoh8nrzeiqn44 X-Rspamd-Queue-Id: 70370C0003 X-Rspam-User: X-HE-Tag: 1793802730-214774 X-HE-Meta: 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 Xm2Qj00O cpPuwN5lg1GC5tBsVDeLdFug8bCLHSJIO5YcRDaIi5X42IogwnYWz1BJgrB6jghmxCxDDf5fKAtb0HGDLvY9vtot59PLxVa2HGzC/wvnboPSo7YDd/A0qLbyd/rQAeIn9chNBln2sS2oQMmuLBuEwitfuPs370fBLEuyDxcgdbGLmnxf4aoD66OfhAh9GDpX56iS7CFErj5987sll6OtzgL0/Rh2GFtBZCrIcWfshZ3L49gec2O1ABveLPneo1qN5r6Mx8VyPT5bMadyVEZf2gmYojimayFEfTgyK Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 03 2026, David Matlack wrote: > Handle a failure to add a retrieved file to luo_preserved_files instead > of triggering a WARN_ON(). Make the failure permanent, and keep the file > until the file set is finished, like any other retrieved file. > > xa_insert() can fail with -ENOMEM, and userspace can trigger that with > LIVEUPDATE_SESSION_RETRIEVE_FD, so warning about it lets userspace crash > systems with panic_on_warn. > > The handler has already consumed the preserved state when this happens, > so the retrieve can't be retried. Keeping the file ensures that its > resources are not released before the file set is finished. Finishing > the file set then erases the file from luo_preserved_files, which does > nothing for a file that was never added. > > Fixes: 00d0b372374f ("liveupdate: prevent double management of files") > Signed-off-by: David Matlack > Acked-by: Pasha Tatashin > --- > kernel/liveupdate/luo_file.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c > index 908ae124ea5e..5a82e45b9062 100644 > --- a/kernel/liveupdate/luo_file.c > +++ b/kernel/liveupdate/luo_file.c > @@ -684,14 +684,25 @@ int luo_retrieve_file(struct luo_file_set *file_set, u64 token, u64 arg, > return err; > } > > + err = xa_insert(&luo_preserved_files, > + luo_get_id(luo_file->fh, args.file), args.file, > + GFP_KERNEL); > + if (err) { I think you should do a WARN_ON_ONCE(err == -EBUSY) here. Because if someone can somehow retrieve the same file twice, something really bad has happened and must be reported. > + /* > + * The handler has consumed the preserved state, so the retrieve > + * can't be retried. Keep the file until the file set is > + * finished, so that its resources are released at the same > + * time as those of other retrieved files. > + */ > + luo_file->file = args.file; > + luo_file->retrieve_status = err; > + return err; > + } > + > luo_file->file = args.file; > /* Get reference so we can keep this file in LUO until finish */ > get_file(luo_file->file); > > - WARN_ON(xa_insert(&luo_preserved_files, > - luo_get_id(luo_file->fh, luo_file->file), > - luo_file->file, GFP_KERNEL)); > - > *filep = luo_file->file; > luo_file->retrieve_status = 1; -- Regards, Pratyush Yadav