From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794320625; b=G38gLaa/PlE48i1n0/NkwIJz0FMxMKk+l7YNSlR0PlIGzSfw4dFLaQq7kkjqOeIuU/2V MKw35ge++8ln4BIc+cvZHQo5A9pWXwHdQZY5jAYdeM1xpxkuDodrGqXImlnC+vS23dSk8 m9CRnllaSMNtELJuV8anoMw6QTtw7vT1PGfIKuyEBwIvy+MbmmjqfWY86esQXEGByX53q /CXJY/Xt8zMd0pPBwzBEnhGuxysjS/Xv0QoM5lGA5zzHPxmF2bUE1bBs2AY07XJEjb5U+ IhOgBZW1fUqJKH/XDaznTkiAjTb7Pr0A61ainKPOXoHlsm+VoJ5He5j6ngwxN4FyMDg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794320625; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=MFHhV6JV3duPdWlAwTgNl2405AjB2zbzyR5W6vvdjbs=; b=Jto6mZHL4YOBgiOG6AZ/hwNDuPr4DFnfbasq7O7j72zipcRNFtB//LawgFxq9/6cc29k /3hqRTuR0yu6voa10GMbLaxq8GejY2hFEnDUDxxuaXZ7ln9eeb7IO2Y/j565aU8CxJAMa zIFqxwwS/QsmJhSbbkEoM3gbKwTQdloMMD1mipmVY9h1JeXt3TL5Easft84ZTvHo+KYNq 3Qrb+j5t0U0USTouPH4gv26NsGib6p0tNdIuyOOSWKCAhwEQwQsR6lUXkFm9EbMiKPx9j wNxRJjaLpjjgea1fw5Cpb5uExj2qB1iOZkl8FRd+Aw4289J0PHJeezE3l/d+Lvd/q+g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CA6hh4Nn; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A3239606A321 for ; Tue, 10 Nov 2026 14:23:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CA6hh4Nn Received: by smtp.kernel.org (Postfix) with ESMTPSA id 845061F008A4; Tue, 10 Nov 2026 14:23:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794320624; bh=MFHhV6JV3duPdWlAwTgNl2405AjB2zbzyR5W6vvdjbs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CA6hh4Nn3sB9vdG6FQ2j4ZkZ+X0EcdUeRHyjEy5IOQDWDz5sf+deVAdp9mITVWfM2 JNuAiV1lJDGMWOCuJi7iPImpSghMtUkKplIaIlux4X1kq8pBc0dW1HpftRaG2nvTNW 83ISg7MGVCAmLRo7nc0SaGpJZJbJ966Cq1s/S9YHHYeyBE+mlBMRxgSxpReRm28Znk KLCX1QziEsWoqvfk1xu5pNkn1tL84xJrh/O13+8CdX1aeIHBg46hnB68nzo57+z7cl yNMS9Exy6OmRqF3zpE4fOOap5vlkK6bLyLC8Eo1nZZ8W0WJJ7U+LvtFqPIlws/6wUO 2aLMOtreAxpZA== From: Sasha Levin To: stable@vger.kernel.org Cc: Sergey Senozhatsky , stable@kernel.org, Sarthak Kukreti , Jan Kara , Baokun Li , Zhang Yi , Theodore Ts'o , Sasha Levin Subject: [PATCH 6.6.y 2/2] ext4: fix ABBA deadlock in ext4_rmdir() Date: Tue, 10 Nov 2026 09:23:41 -0500 Message-ID: <20261110142328.1870404-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110142328.1870404-1-sashal@kernel.org> References: <20261107053253-failed-6.6-19e16597f9ba@kernel.org> <20261110142328.1870404-1-sashal@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sergey Senozhatsky [ Upstream commit 19e16597f9baf1b5719a3a6c710486446f6808fd ] We observe the following ABBA deadlock (casefolding enabled): INFO: task jbd2/dm-13-8:447 blocked for more than 720 seconds. task:jbd2/dm-13-8 state:D stack:0 pid:447 tgid:447 ppid:2 Call Trace: __schedule+0xc2c/0xe60 schedule+0x40/0xe0 jbd2_journal_wait_updates+0x8f/0xf0 jbd2_journal_commit_transaction+0x321/0x1850 kjournald2+0xa9/0x230 kthread+0x226/0x2a0 ret_from_fork+0x101/0x1e0 ret_from_fork_asm+0x1a/0x30 INFO: task Thread-10:4161 blocked for more than 720 seconds. task:Thread-10 state:D stack:0 pid:4161 tgid:3848 ppid:540 Call Trace: __schedule+0xc2c/0xe60 schedule+0x40/0xe0 wait_transaction_locked+0x8c/0xd0 start_this_handle+0x252/0x870 jbd2__journal_start+0x120/0x280 __ext4_journal_start_sb+0x11a/0x250 ext4_evict_inode+0x208/0x760 iput+0x222/0x5c0 dput+0x293/0x690 ____fput+0x145/0x2b0 task_work_run+0x7a/0xb0 exit_to_user_mode_loop+0xc0/0xd0 do_syscall_64+0x14b/0xf10 entry_SYSCALL_64_after_hwframe+0x76/0x7e NMI backtrace for cpu 0 CPU: 0 UID: 1010216 PID: 4160 Comm: Thread-7 RIP: 0010:d_walk+0x0/0x290 [..] Call Trace: shrink_dcache_parent+0xb2/0x100 d_invalidate+0x50/0x110 ext4_rmdir+0x3a2/0x3d0 vfs_rmdir+0x9d/0x1d0 do_rmdir+0xf0/0x330 __x64_sys_unlinkat+0x34/0x50 do_syscall_64+0x61/0xf10 The problem is that ext4_rmdir() calls d_invalidate() before stopping the jbd2 transaction handle. Because d_invalidate() traverses child dentries it can encounter dying or in-use dentries. If a concurrent thread executing __dentry_kill() on a child dentry invokes ext4_evict_inode(), it requests a new transaction handle via ext4_journal_start(), which waits for all running handles to close. However, the thread executing ext4_rmdir() still holds its active transaction handle while looping in shrink_dcache_parent() waiting for the dying child dentry to complete eviction. Stop transaction handle in ext4_rmdir() before calling d_invalidate(). Cc: stable@kernel.org Fixes: b886ee3e778e ("ext4: Support case-insensitive file name lookups") Co-developed-by: Sarthak Kukreti Signed-off-by: Sarthak Kukreti Signed-off-by: Sergey Senozhatsky Reviewed-by: Jan Kara Reviewed-by: Baokun Li Reviewed-by: Zhang Yi Link: https://patch.msgid.link/20260827125158.4030598-1-senozhatsky@chromium.org Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/namei.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index c77a18ce76bc7..b30ddb3750fd4 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3259,19 +3259,20 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry) ext4_fc_track_unlink(handle, dentry); retval = ext4_mark_inode_dirty(handle, dir); +end_rmdir: + brelse(bh); + if (handle) + ext4_journal_stop(handle); + /* VFS negative dentries are incompatible with Encoding and * Case-insensitiveness. Eventually we'll want avoid * invalidating the dentries here, alongside with returning the * negative dentries at ext4_lookup(), when it is better * supported by the VFS for the CI case. */ - if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) + if (!retval && IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) d_invalidate(dentry); -end_rmdir: - brelse(bh); - if (handle) - ext4_journal_stop(handle); return retval; } -- 2.53.0