From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 11C2443BDBF for ; Thu, 20 Aug 2026 11:49:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787226554; cv=none; b=P39r5w4exqRxB7SghcalJC9FEshwjS473OwL2DuHUwL5D+xqpoBA3HV6ehecseoWcplAAfo8iHhSqBGsM/FuZa5Hrb0SqTzMlSWpX1q9oremrgAoWrXsW4ZH1l+yWlEgPdgGXhktsu+mry+3zZ1PVc1GBYqPoXwqbsIju+eShac= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787226554; c=relaxed/simple; bh=gWXn1MNZRfh09/A2Mq/5qIlYKRWg92iEr2FXPUe6T24=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=uAUvMN+Y6dH+5m2deVd0DEnX5JKCFSVr2RCZ5YIhvsK9+61VicG+hKM2aveuSQrevDvvtXMRbMp7qodAN1+s3jX491JUdl1wji+XMosq9N9UCbwUwMc+I93OKq5MhzItzFcKm6Gxo7c2WPh9e4ZpA640G6t3LcBs7VFRHKdNkI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tEsZOIrN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tEsZOIrN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E3701F000E9; Thu, 20 Aug 2026 11:49:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787226548; bh=CP392cVD/bU/k3IoI9fH4zAVfERk2KuhsuRp9dPB8t8=; h=Subject:To:Cc:From:Date; b=tEsZOIrN63bm+VlLsyAyTKzEnk8mjA74HZzLJ30RR4y0K7OoxcpXGy8J1lPwJwDnj d+HhkMBr8nUyI8ngyYmK2iS7NrqnR8IqmyD3nfuuGDRQF0V3+2OwGRtcCNHWYPuxyO dxfeYxax50DAJLyc/s/83wJ0fpYy/D/FFvnRH5DE= Subject: FAILED: patch "[PATCH] xfs: don't livelock in scrub on a circular unlinked list" failed to apply to 6.18-stable tree To: djwong@kernel.org,cem@kernel.org,hch@lst.de Cc: From: Date: Thu, 20 Aug 2026 13:37:43 +0200 Message-ID: <2026082043-rely-pentagram-07de@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 527eaaefddb6ec5c83a06c9a1559960dd6361753 # git commit -s git send-email --to '' --in-reply-to '2026082043-rely-pentagram-07de@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 527eaaefddb6ec5c83a06c9a1559960dd6361753 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Sun, 26 Jul 2026 22:24:48 -0700 Subject: [PATCH] xfs: don't livelock in scrub on a circular unlinked list LOLLM points out that online fsck can livelock if an unlinked inode list contains a loop. Use a bitmap to detect cycles. Cc: stable@vger.kernel.org # v4.15 Fixes: a12890aebb8959 ("xfs: scrub the AGI") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c index cecf034ef989..1fa66aa68e16 100644 --- a/fs/xfs/scrub/agheader.c +++ b/fs/xfs/scrub/agheader.c @@ -18,6 +18,8 @@ #include "xfs_inode.h" #include "scrub/scrub.h" #include "scrub/common.h" +#include "scrub/bitmap.h" +#include "scrub/agino_bitmap.h" int xchk_setup_agheader( @@ -935,7 +937,8 @@ xchk_agi_xref( /* * Walk the incore unlinked list for a particular AGI bucket to construct * the unlinked inode bitmap for later reconstruction of the unlinked list. - * Returns 1 if we should keep checking, or 0 to stop checking. + * Returns 1 if we should keep checking, 0 to stop checking, or a negative + * errno. */ static int xchk_iunlink_bucket( @@ -943,36 +946,57 @@ xchk_iunlink_bucket( unsigned int bucket, xfs_agino_t agino) { + struct xagino_bitmap seen; + int ret; + + xagino_bitmap_init(&seen); + while (agino != NULLAGINO) { struct xfs_inode *ip; + unsigned int len = 1; if (agino % XFS_AGI_UNLINKED_BUCKETS != bucket) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; + } + + if (xagino_bitmap_test(&seen, agino, &len)) { + xchk_block_set_corrupt(sc, sc->sa.agi_bp); + goto bad; } ip = xfs_iunlink_lookup(sc->sa.pag, agino); if (!ip) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; } if (!xfs_inode_on_unlinked_list(ip)) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; } + ret = xagino_bitmap_set(&seen, agino, 1); + if (ret) + goto out_bitmap; + agino = ip->i_next_unlinked; } + ret = 1; - return 1; +out_bitmap: + xagino_bitmap_destroy(&seen); + return ret; +bad: + ret = 0; + goto out_bitmap; } /* * Check the unlinked buckets for links to bad inodes. We hold the AGI, so * there cannot be any threads updating unlinked list pointers in this AG. */ -STATIC void +STATIC int xchk_iunlink( struct xfs_scrub *sc, struct xfs_agi *agi) @@ -985,8 +1009,10 @@ xchk_iunlink( ret = xchk_iunlink_bucket(sc, i, be32_to_cpu(agi->agi_unlinked[i])); if (ret < 1) - return; + return ret; } + + return 0; } /* Scrub the AGI. */ @@ -1073,7 +1099,9 @@ xchk_agi( if (pag->pagi_freecount != be32_to_cpu(agi->agi_freecount)) xchk_block_set_corrupt(sc, sc->sa.agi_bp); - xchk_iunlink(sc, agi); + error = xchk_iunlink(sc, agi); + if (error) + goto out; xchk_agi_xref(sc); out: diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c index 2554494847ff..13074d5e319c 100644 --- a/fs/xfs/scrub/agheader_repair.c +++ b/fs/xfs/scrub/agheader_repair.c @@ -1080,18 +1080,22 @@ xrep_iunlink_walk_ondisk_bucket( struct xrep_agi *ragi, unsigned int bucket) { + struct xagino_bitmap seen; struct xfs_scrub *sc = ragi->sc; struct xfs_agi *agi = sc->sa.agi_bp->b_addr; xfs_agino_t prev_agino = NULLAGINO; xfs_agino_t next_agino; int error = 0; + xagino_bitmap_init(&seen); + next_agino = be32_to_cpu(agi->agi_unlinked[bucket]); while (next_agino != NULLAGINO) { xfs_agino_t agino = next_agino; + unsigned int len = 1; if (xchk_should_terminate(ragi->sc, &error)) - return error; + goto out_bitmap; trace_xrep_iunlink_walk_ondisk_bucket(sc->sa.pag, bucket, prev_agino, agino); @@ -1099,15 +1103,24 @@ xrep_iunlink_walk_ondisk_bucket( if (bucket != agino % XFS_AGI_UNLINKED_BUCKETS) break; + if (xagino_bitmap_test(&seen, agino, &len)) + break; + next_agino = xrep_iunlink_next(sc, agino); if (!next_agino) next_agino = xrep_iunlink_reload_next(ragi, prev_agino, agino); + error = xagino_bitmap_set(&seen, agino, 1); + if (error) + goto out_bitmap; + prev_agino = agino; } - return 0; +out_bitmap: + xagino_bitmap_destroy(&seen); + return error; } /* Decide if this is an unlinked inode in this AG. */