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=1794321095; b=XfFobo0EazeNZUjCh9811pxiABJ7tRz7/JUlSf7imiP70V4nt7KNGoD52EQ2OiBPF+Yx beEkef7Iu0O/LwGocRRixL6hV9yEpDcWbF6/9SOt4iL8BVyvhSEQnzu/Szznmgcqbyyd8 2UyN331VVC96AOV1nokEaRGCvks+NBAVq0FGBsa2SQihdGPd+51lES6Fudi2xETzDLakN ZjxvPbw+yUC2EunzIpvfaGhk2aEiW49Zu88FBpQMl9gIOisnt9VLJZ91rpaGrb94R0RvA AahnBYVARn9uJC35tFi3g0d531T04fAGxJDYVkj3OeTH6WkijEGJ9UQXoF22122GtKg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794321095; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=msh1AWpq3zPxJUG9yN+IS+TEgC0i10NhoeOOq9d3EPs=; b=F2v94bOug8vN4yOTI3X1sQBQvhNX23bJNOqOlunI+0L5UZk9ca0mbWckxKyZ9zs1I8NH tH4vkKmbHRJ6vmkrSAyaXiT/eGBDLfAocPdSC4EfqEiXeLuj+63VSse8CtHjXeLcyjt6U 8rhDycMS3/YSUieTnuhutgLQE2Tct4U12a5aLLy1jWOitFfF6zkNiGj+MIDEa6Kybmeep qLPSC+H5Yj3rD+KJAQeZN9n6r14cuqSyh+qqBe3q1uloWrnhmMqQWDAgaQE0wSRAKwmDC 7Q5NwEqmC7JYRSEh8b7EdJyHCyTTzPAKozxZTY8uJ75/URBoJUMqu8BnPf4niwKrKkw== 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=M8wHUA3g; 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 3F987606A321 for ; Tue, 10 Nov 2026 14:31:35 +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=M8wHUA3g Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2007C1F008BD; Tue, 10 Nov 2026 14:31:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794321095; bh=msh1AWpq3zPxJUG9yN+IS+TEgC0i10NhoeOOq9d3EPs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M8wHUA3gGNUK4Sg+L7Qp5f7sw0xUDLw2uj70uc/AvpC5sRTSUfukEWDStuXD8iGG1 UyMrIvbr0v207+hHzgJgkYxAWK7jVRp4xX5qa3kaNoVCcF21PPwVhYOAFP6qPtnyV0 P4/sKjgc/01EDGHDOcYJ2uxecDWiixhDS8WURERqFPA31BR6+nvAo2y7OnSMPQ+Q7d gZucqrts8UHgfAbf3FARbvqJeQrRtPThUMEWn2Eto6FZo7s5nUWzxRUKR+W1TC5k/0 caNrr0nPr8bRsE46IUw87CvthAc9s1LmkLEWWRlpAjMTFlrkHky8oi5Mtfpd4SUxhT OtwhBIVpTptxg== 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 6.1.y 2/2] ext4: fix ABBA deadlock in ext4_rmdir() Date: Tue, 10 Nov 2026 09:31:31 -0500 Message-ID: <20261110143124.1907093-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261110143124.1907093-1-sashal@kernel.org> References: <20261107054551-failed-6.1-19e16597f9ba@kernel.org> <20261110143124.1907093-1-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 e38770a7ce444..42cc5c8778444 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3258,19 +3258,20 @@ 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