From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5F4D12F25F4 for ; Thu, 2 Apr 2026 16:31:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775147480; cv=none; b=KeBqlIFw2JBJPZTYV+5uoTTUFkE6DzP+w5CaT6A5vbcut/k9GKhIH765VR3hqn2PAqS4oemS1e7Yfzdbyjfm8lpdgbghpjYtjhYy6c6b9Pu3NYotoX0p2dwgYKd9SyomwxMaRqEHJFrkro+ddTlgzEIoAw+0SgRfphAK7qquVpM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775147480; c=relaxed/simple; bh=62nh+2Cv/KZUF06cF/IIBz0VU2JqGZSBM8siTgX2HHw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CUX20+9TbhaiM6lyoGx0rF2gQ/NJj9sS7ZbhoAz+BC53X68u9JVVCBhr8BZuByfTilrLKOowZwQ2FOIf9OMsdI1jW8XkbHJKr6hZauIdqV/EVZrTe50RLbkqN6A6inlpcWmrDaTYZEM13VideaflEUReWVdWzqM23+lOvPqp8n8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P8ZYNlN7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P8ZYNlN7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6A20DC19423; Thu, 2 Apr 2026 16:31:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775147480; bh=62nh+2Cv/KZUF06cF/IIBz0VU2JqGZSBM8siTgX2HHw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P8ZYNlN79JKvnb1GjTNYeES1+3OUBXtCdRcWVezA2j/mIUk6WNJtn7puzc76BxtWS WaeJAS5WAwNn7nG+7dL/m1U3YPAGu0nJgMurpZIhoKBWQKusQ2Oot/mIMueu2Yo2l1 kOEQid3OfCcHxukfdkOJS0PjjrPvLa6lT07JR//m6bkVIUDhFSw+7OmKYpnFwg4vdf yMkj5S5/pW5hOC/Zh9DOtj5MVZcGx/5f8yXP+K1P5MzRPKEZoJXaY43+1nrsBsoKgl laHqpX4nnraDFUpFAsyykmvBqEDtWXnFRar3sS/WAddvUIUCBK3Y+D3C6eA/1KLFd3 rRV+64R8zgG1A== From: Sasha Levin To: stable@vger.kernel.org Cc: Zqiang , Baokun Li , Theodore Ts'o , stable@kernel.org, Sasha Levin Subject: [PATCH 6.1.y 4/4] ext4: fix the might_sleep() warnings in kvfree() Date: Thu, 2 Apr 2026 12:31:15 -0400 Message-ID: <20260402163115.1385749-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260402163115.1385749-1-sashal@kernel.org> References: <2026033016-eagle-gangrene-7fc7@gregkh> <20260402163115.1385749-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zqiang [ Upstream commit 496bb99b7e66f48b178126626f47e9ba79e2d0fa ] Use the kvfree() in the RCU read critical section can trigger the following warnings: EXT4-fs (vdb): unmounting filesystem cd983e5b-3c83-4f5a-a136-17b00eb9d018. WARNING: suspicious RCU usage ./include/linux/rcupdate.h:409 Illegal context switch in RCU read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 Call Trace: dump_stack_lvl+0xbb/0xd0 dump_stack+0x14/0x20 lockdep_rcu_suspicious+0x15a/0x1b0 __might_resched+0x375/0x4d0 ? put_object.part.0+0x2c/0x50 __might_sleep+0x108/0x160 vfree+0x58/0x910 ? ext4_group_desc_free+0x27/0x270 kvfree+0x23/0x40 ext4_group_desc_free+0x111/0x270 ext4_put_super+0x3c8/0xd40 generic_shutdown_super+0x14c/0x4a0 ? __pfx_shrinker_free+0x10/0x10 kill_block_super+0x40/0x90 ext4_kill_sb+0x6d/0xb0 deactivate_locked_super+0xb4/0x180 deactivate_super+0x7e/0xa0 cleanup_mnt+0x296/0x3e0 __cleanup_mnt+0x16/0x20 task_work_run+0x157/0x250 ? __pfx_task_work_run+0x10/0x10 ? exit_to_user_mode_loop+0x6a/0x550 exit_to_user_mode_loop+0x102/0x550 do_syscall_64+0x44a/0x500 entry_SYSCALL_64_after_hwframe+0x77/0x7f BUG: sleeping function called from invalid context at mm/vmalloc.c:3441 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 556, name: umount preempt_count: 1, expected: 0 CPU: 3 UID: 0 PID: 556 Comm: umount Call Trace: dump_stack_lvl+0xbb/0xd0 dump_stack+0x14/0x20 __might_resched+0x275/0x4d0 ? put_object.part.0+0x2c/0x50 __might_sleep+0x108/0x160 vfree+0x58/0x910 ? ext4_group_desc_free+0x27/0x270 kvfree+0x23/0x40 ext4_group_desc_free+0x111/0x270 ext4_put_super+0x3c8/0xd40 generic_shutdown_super+0x14c/0x4a0 ? __pfx_shrinker_free+0x10/0x10 kill_block_super+0x40/0x90 ext4_kill_sb+0x6d/0xb0 deactivate_locked_super+0xb4/0x180 deactivate_super+0x7e/0xa0 cleanup_mnt+0x296/0x3e0 __cleanup_mnt+0x16/0x20 task_work_run+0x157/0x250 ? __pfx_task_work_run+0x10/0x10 ? exit_to_user_mode_loop+0x6a/0x550 exit_to_user_mode_loop+0x102/0x550 do_syscall_64+0x44a/0x500 entry_SYSCALL_64_after_hwframe+0x77/0x7f The above scenarios occur in initialization failures and teardown paths, there are no parallel operations on the resources released by kvfree(), this commit therefore remove rcu_read_lock/unlock() and use rcu_access_pointer() instead of rcu_dereference() operations. Fixes: 7c990728b99e ("ext4: fix potential race between s_flex_groups online resizing and access") Fixes: df3da4ea5a0f ("ext4: fix potential race between s_group_info online resizing and access") Signed-off-by: Zqiang Reviewed-by: Baokun Li Link: https://patch.msgid.link/20260319094545.19291-1-qiang.zhang@linux.dev Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Sasha Levin --- fs/ext4/mballoc.c | 10 +++------- fs/ext4/super.c | 8 ++------ 2 files changed, 5 insertions(+), 13 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index e204f16e33ad3..9127e5184c1ae 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3294,9 +3294,7 @@ static int ext4_mb_init_backend(struct super_block *sb) rcu_read_unlock(); iput(sbi->s_buddy_cache); err_freesgi: - rcu_read_lock(); - kvfree(rcu_dereference(sbi->s_group_info)); - rcu_read_unlock(); + kvfree(rcu_access_pointer(sbi->s_group_info)); return -ENOMEM; } @@ -3595,7 +3593,8 @@ int ext4_mb_release(struct super_block *sb) WARN_ON_ONCE(!list_empty(&sbi->s_discard_list)); } - if (sbi->s_group_info) { + group_info = rcu_access_pointer(sbi->s_group_info); + if (group_info) { for (i = 0; i < ngroups; i++) { cond_resched(); grinfo = ext4_get_group_info(sb, i); @@ -3613,12 +3612,9 @@ int ext4_mb_release(struct super_block *sb) num_meta_group_infos = (ngroups + EXT4_DESC_PER_BLOCK(sb) - 1) >> EXT4_DESC_PER_BLOCK_BITS(sb); - rcu_read_lock(); - group_info = rcu_dereference(sbi->s_group_info); for (i = 0; i < num_meta_group_infos; i++) kfree(group_info[i]); kvfree(group_info); - rcu_read_unlock(); } kfree(sbi->s_mb_avg_fragment_size); kfree(sbi->s_mb_avg_fragment_size_locks); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 85286a50dcb2f..c004aaa722201 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1241,12 +1241,10 @@ static void ext4_group_desc_free(struct ext4_sb_info *sbi) struct buffer_head **group_desc; int i; - rcu_read_lock(); - group_desc = rcu_dereference(sbi->s_group_desc); + group_desc = rcu_access_pointer(sbi->s_group_desc); for (i = 0; i < sbi->s_gdb_count; i++) brelse(group_desc[i]); kvfree(group_desc); - rcu_read_unlock(); } static void ext4_flex_groups_free(struct ext4_sb_info *sbi) @@ -1254,14 +1252,12 @@ static void ext4_flex_groups_free(struct ext4_sb_info *sbi) struct flex_groups **flex_groups; int i; - rcu_read_lock(); - flex_groups = rcu_dereference(sbi->s_flex_groups); + flex_groups = rcu_access_pointer(sbi->s_flex_groups); if (flex_groups) { for (i = 0; i < sbi->s_flex_groups_allocated; i++) kvfree(flex_groups[i]); kvfree(flex_groups); } - rcu_read_unlock(); } static void ext4_put_super(struct super_block *sb) -- 2.53.0