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=1793560922; b=WbURZaq3H2DvUs2zbaxx0/vrFzhix+XN0yjZ9OzYS4GRw0/QNaXgxLYQG3+UvJOhQeLI 4KxYQMR26ViIAYdY0L/Ga/3En15qz/8JtYhca5Lp1U2veBtkNO4OY61HwEicO2kZr7NoP 07/BZUff36EMEJIjuQxI5/zcM0hWKy7yGV9kUuXNW/JKGKg6gqe+n0uO+tpf+vA8+7bsV 6tJhIP9+BRovtkXRIYTN4JxfuTqv8LeaZmjgB6Zf5pCiuPFJmYYzf1uyN9BY8DrG69Wzv wiJZGbsuf5avJgaE5n92m/SVo/yW90Wu0UmHBk00RS7RD+QfWTE0bpmG6dQMjbK8UBQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793560922; h=Received:DKIM-Signature:Date:To:From:Subject:Message-Id; bh=AA0+NJqAFeqIItjoAyZ4cTNOnziC1aV+qwEWlSoDoT0=; b=QnK7FnE0XLZqiu1mXBfl71sLCvcAHdQXeqnsLoxDRAFU2UUyPpclfF9ThM0kgn47tc28 YZYTB96uwl4nF2+aq9VHifktgbDZPsIxmyRW4kEVEyGwj85vEQsne+JscTteqqIanUC3q S8VM60orLgzmd+NzBn1BAEwRkioCttUx0TlbbglzIf+iuFSGX4cO4zjzK9dPUWoLtPvZv lskbTnAUTkL+2rgdow8OM7J8UZOELJ0K4G4iouD/eQygpdoGUGCzSmenn4oVg3eKUD4Ep aYNkup9vQLJ6lV3MlqRHmyOcvhQYhHJKBo7Y3nsGN77vdmMy/B9pBWbXxcZi9e1hLRw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=kSIXOR05; 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 2AC6E606A324; Sun, 1 Nov 2026 19:22:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=kSIXOR05 Received: by smtp.kernel.org (Postfix) with ESMTPSA id D08261F00919; Sun, 1 Nov 2026 19:22:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1793560921; bh=AA0+NJqAFeqIItjoAyZ4cTNOnziC1aV+qwEWlSoDoT0=; h=Date:To:From:Subject; b=kSIXOR05DNXlg2ozq6FVUww+3Y4tqfUvN+oLqonPUqRnu1h+YaDefQfQ9BcygWd1R LDXF5YAr09VqF5RxmWQSzqi8nV+cK+dKBXscEXNMe8hciErZZAXaDRLz1LFyhYw6ND 5oK7G6nOcS5S/WuOEfW5kCLNtF6WOPu8ApfgBnCA= Date: Sun, 01 Nov 2026 11:22:01 -0800 To: mm-commits@vger.kernel.org, syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com,stable@vger.kernel.org, osalvador@suse.de,muchun.song@linux.dev,lihongbo22@huawei.com, david@kernel.org,joasantonio108@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode.patch added to mm-hotfixes-unstable branch Message-Id: <20261101192201.D08261F00919@smtp.kernel.org> X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list The patch titled Subject: hugetlbfs: move hugetlbfs_free_inode tracepoint to ->destroy_inode() has been added to the -mm mm-hotfixes-unstable branch. Its filename is hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Joas Antonio dos Santos Subject: hugetlbfs: move hugetlbfs_free_inode tracepoint to ->destroy_inode() Date: Sun, 01 Nov 2026 13:48:55 +0000 hugetlbfs_free_inode() calls trace_hugetlbfs_free_inode(), and the hugetlbfs__inode event class records inode->i_sb->s_dev. ->free_inode() runs from an RCU callback (destroy_inode() queues i_callback() with call_rcu()), and Documentation/filesystems/porting.rst says that this callback "is *NOT* ordered wrt superblock destruction; as the matter of fact, the superblock and all associated structures might be already gone". put_super() frees the superblock with call_rcu() followed by a workqueue item (destroy_super_rcu() -> destroy_super_work()). syzbot hit this with the event enabled: BUG: KASAN: slab-use-after-free in trace_event_raw_event_hugetlbfs__inode+0x45b/0x4c0 include/trace/events/hugetlbfs.h:36 Read of size 4 at addr ffff888038850010 by task syz-executor952/6134 hugetlbfs_free_inode+0x15e/0x1f0 fs/hugetlbfs/inode.c:1182 i_callback+0x46/0x80 fs/inode.c:317 rcu_do_batch kernel/rcu/tree.c:2650 [inline] rcu_core+0x5f0/0x1220 kernel/rcu/tree.c:2919 Allocated by task 6134: alloc_super fs/super.c:326 [inline] sget_fc+0x1ba/0x1f60 fs/super.c:874 hugetlbfs_get_tree+0x1e7/0x2b0 fs/hugetlbfs/inode.c:1431 Freed by task 855: kfree+0x22b/0x6d0 mm/slub.c:6923 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495 Emit the event from hugetlbfs_destroy_inode() instead. destroy_inode() calls ->destroy_inode() synchronously, before it queues the RCU callback, while the superblock is still alive; hugetlbfs_destroy_inode() already dereferences inode->i_sb there. ->free_inode() is left with only the kmem_cache_free(). Since the event no longer fires from ->free_inode(), rename it to hugetlbfs_destroy_inode so that its name matches where it is emitted, as suggested by David and Muchun. Found by syzbot; analysed and tested with the syzbot C reproducer on an arm64 KASAN kernel. Link: https://lore.kernel.org/20261101-b4-hugetlbfs-trace-v3-1-051b716f490f@gmail.com Fixes: 014ad7c42a69 ("hugetlbfs: use tracepoints in hugetlbfs functions.") Signed-off-by: Joas Antonio dos Santos Signed-off-by: Andrew Morton Reported-by: Closes: https://lore.kernel.org/all/6ae27525.5451848c.f7707.0001.GAE@google.com/ Suggested-by: David Hildenbrand Suggested-by: Muchun Song Cc: Oscar Salvador Cc: Hongbo Li Cc: --- fs/hugetlbfs/inode.c | 6 +++++- include/trace/events/hugetlbfs.h | 2 +- 2 files changed, 6 insertions(+), 2 deletions(-) --- a/fs/hugetlbfs/inode.c~hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode +++ a/fs/hugetlbfs/inode.c @@ -1179,12 +1179,16 @@ static struct inode *hugetlbfs_alloc_ino static void hugetlbfs_free_inode(struct inode *inode) { - trace_hugetlbfs_free_inode(inode); kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode)); } static void hugetlbfs_destroy_inode(struct inode *inode) { + /* + * Not in ->free_inode(): that runs from an RCU callback, when the + * superblock the event reads may already be freed. + */ + trace_hugetlbfs_destroy_inode(inode); hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb)); } --- a/include/trace/events/hugetlbfs.h~hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode +++ a/include/trace/events/hugetlbfs.h @@ -72,7 +72,7 @@ DEFINE_EVENT(hugetlbfs__inode, hugetlbfs TP_ARGS(inode) ); -DEFINE_EVENT(hugetlbfs__inode, hugetlbfs_free_inode, +DEFINE_EVENT(hugetlbfs__inode, hugetlbfs_destroy_inode, TP_PROTO(struct inode *inode), _ Patches currently in -mm which might be from joasantonio108@gmail.com are hugetlbfs-move-hugetlbfs_free_inode-tracepoint-to-destroy_inode.patch