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=1793626153; b=0Dg2CBuRJmSwCm3nTRewI2DBA3vRGJ4YOMe3H68WtZvxXXUrYZV14ZOTVYOBeynNPhs+ UfrKx8BKYm0GwJcFftCDw8x6H6vWxys6711IDvNcV3NuetdldUfBoe4Z2KGxM7Yzgz50p OgC4URaVa8RZq3kCxz4kxNgCjNrSuU6AOy0VJ6Cx5HSVtl6QRvdpwRaGut383fQxRShxc g3y1ECxbQrQBVvVBhi6XQ1ZjIhLk3xHLdn+1MDGuA5zxwfKTOf9SSX7axK9Mft8pj0Spm ygkpCYLzGRuB16+Kjtjr4hAYGgwCsrChaT3FpEGgLQuvNl/eingnf5HFGakoSswP3ew== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793626153; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=c4mwdoBV41dp/el9UexkE6PaovCoClxCt2msJtff3Ts=; b=yByqtmN2J3CYe/vibsNu/lUqXW2viaCDU8/RGyUCn7MGb3PrPTHPYo98Y6fT0tsFzl7B QePOevfUAUqEPVAMu2bLK6gHMGJqwK0OsyFDAyeJaJK69AbWoTVqE4zZMGt7kzSYrvPt9 lb+jXe/6WgPqXRmmbj+iP9VtlHR+/IuDFy9cJ9k0+mhfMvPJ5pNgqJZGmLecli7fu8l9q TorC7Tl2SeXPDLcE7vG68TdqzjAt0vOHW0K8yxtr9EU63UFJTzhBLn3eSIkdYdZ7qYLQ8 9Wz4unkaHchRHhQQEg7USctyE+xxSqLxAolGK5J7tOUA+LlVi3fsOO0tTDIWVSIyYIg== 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=j+tMVeM4; 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 AB120606A327; Mon, 2 Nov 2026 13:29:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=j+tMVeM4 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A32E1F00A16; Mon, 2 Nov 2026 13:29:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793626152; bh=c4mwdoBV41dp/el9UexkE6PaovCoClxCt2msJtff3Ts=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=j+tMVeM4+zVoOaokgN4+z2ABMaFyx62kJXGZeUYiddLOI7ya2VQzvEgnENNmBa+HY WanULjAu8qaoAGkhVnJaxnN1pfDhTONL2Lv4h+4CfZHpVj7/Xkj5ZaQ7LBzjopVqtQ MKc79jBGqYoHhqaOEw1ET3cG2zZJzfc6pfVdLiyVIpRdKcUUC8iryVyLdDv1n15ySv lX/q17qhDw0kvQ5ENIMiEjUJtcR0vDDz5RLx0oHbbD3KqZvzp90IhCvqlUSaG29+pU +5IhfKqpyJKevDpFGEe+FkvAXmSEDC5kpKIGUFG2Hayk5rC5+SRK/NdLt6pDZyNIc2 N8VS5fLE9Fyhg== Message-ID: <5c0c6ce4-ddbd-4b87-a005-17a7b0b837e4@kernel.org> Date: Mon, 2 Nov 2026 14:29:08 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] hugetlbfs: move hugetlbfs_free_inode tracepoint to ->destroy_inode() To: joasantonio108@gmail.com, Muchun Song , Oscar Salvador Cc: linux-mm@kvack.org, Andrew Morton , Hongbo Li , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com, stable@vger.kernel.org References: <20261102-b4-hugetlbfs-trace-v4-1-72371825bb5e@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20261102-b4-hugetlbfs-trace-v4-1-72371825bb5e@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/2/26 14:03, Joas Antonio dos Santos via B4 Relay wrote: > From: Joas Antonio dos Santos > > 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. > > Fixes: 014ad7c42a69 ("hugetlbfs: use tracepoints in hugetlbfs functions.") > Reported-by: syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6ae27525.5451848c.f7707.0001.GAE@google.com/ > Suggested-by: David Hildenbrand > Suggested-by: Muchun Song > Cc: stable@vger.kernel.org > Reviewed-by: Muchun Song > Signed-off-by: Joas Antonio dos Santos > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David