From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EE09C1F5847 for ; Mon, 10 Nov 2025 05:14:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762751691; cv=none; b=mMKBqYjYuaXodwmpejOq76T/BnEPZdJL1a+g+ejixvq0RvX1Ptnt4lwfyLHXGUJNpl5hq7oYINnD49BTM2c1m+DuAZ2VgO5IZ4dHS1vCEqlJZzggChkudDl3ez6febbm6PmUiDxD/mLtyxP0+TdezwbL8pqUMEbwmE5KkNBt3II= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762751691; c=relaxed/simple; bh=LP/krErh2evphX/wAKmsTFB0iANF81HybgXPtXCvaAo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=F458pTHyYbQnwbtF+OhSMdhkAmbaDen+bsKNFOlNlwCjQIyvzFnAhk9Ee3l3roZZShsHB45dlX5UMyONLsmM5R5gIM1pE3hKu1BD2lkXWKkeiPCA98je5p3MS9rlkPxKAX8eGHMbI5q24+ybx/8PVXqDLty1S8Og+BcNIWK+m7Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.216.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pj1-f46.google.com with SMTP id 98e67ed59e1d1-3434700be69so3494287a91.1 for ; Sun, 09 Nov 2025 21:14:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762751689; x=1763356489; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=nCIIbUmCkll5kK4hfoqHENGIwveb/KYptctyAPm2WyQ=; b=YJVxV04hm9r3HYCRQhKT4tYsPEB4uzHJqnmNSYFVhkEf4mwBns5ZDigOPmXhEer4l5 703GX7sDexVLSpfcdEduYttq7ihgO7Wlh9Jx1HgCDuuin1aMSv6xjXTppkL3BgTapcRg kDdnBcM9rHqkE+6AwOVuw+DK5Q19SmmjgEOZGlFZN9UgwUYSyHzRioTIEdk8p/bk8b9L Ae/HSNiEZEGG7rA9zyN6O1yhNpQViAMvuKrzAO+pMZtN5YX8NPuldVRK6708y30fWUun umfwANcmEmMI5E9vOdP9uJ1krorZ1fod1/Su/WrikurbAeNPzLs2czPXGzu+9cc9nHPu y6Qw== X-Forwarded-Encrypted: i=1; AJvYcCUmdxWOfPVv7xJzb6wP65koDMk+mLHzso2CR9QRisqlk2MU/5GO49Q2cMCCJ5o5/cHFSfRJd+xZ35MMwQ4=@vger.kernel.org X-Gm-Message-State: AOJu0Yy7kw9Tx9yD72DeMEeuIuavSYXgsbKqfAXvRPyaEluFlmjEuMbQ VQMydTI4W1zvfA1hn1aWyYZwxGV6Zd4w/oX/ZoQZoxvG0VJvjZ+30JZ9MlkZZA== X-Gm-Gg: ASbGncu2CSsr9nLvy5ia/E7jrD15gSU2S2X5kxxIratTvvioOf/Ai5y1/Y3XmFFAK6L t6IjeivvCqCM1P1uctdEWJfgXez5Wb+HviJS1cR6bt02hUqMeaJ7R2e2Sfxus/kzJcVk3gW+RLY ES3amstRv/B+HKLpanuHGcEpZTxGk0W/FMmpaZRTIL63S2ODz1sIBg2zb9ivYBN5IQYFpx5zMIF kO1KtT9yueHfAoRVe797AX3NfWVb4Mp5lJ+7Xqd0TpNm8nCIii8/5hn3pFfrfppmO39VQnc5KGz bnW9ng/vWwbqwT/72YsMtg0TTT/O5OMyP6LE37yMZ3Sry3Z2Em89YFtHNUlaUcgkhhfUQhRpWTF 921Y1MaJCR5jrgjFNWwfsWY2+Xy1xtiJA6DEaTY8q7L7pB/uKEEqR95XDnFpZg2V/Id7ivtm4EV rjIrKrYIM= X-Google-Smtp-Source: AGHT+IG5OdmbBwJXRmUUCVVuWc4/Mx82Y2ZMrKWq8DF2KYtATXtarldtXNJxCgWZCKf8AgNQKtWNOA== X-Received: by 2002:a17:90b:270a:b0:340:ff89:8b62 with SMTP id 98e67ed59e1d1-3436cbb4076mr8393863a91.21.1762751689221; Sun, 09 Nov 2025 21:14:49 -0800 (PST) Received: from EBJ9932692.tcent.cn ([2403:2c80:17::10:4006]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-341a699c011sm16182816a91.14.2025.11.09.21.14.46 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 09 Nov 2025 21:14:48 -0800 (PST) From: Lance Yang To: akpm@linux-foundation.org Cc: syzbot+3f5f9a0d292454409ca6@syzkaller.appspotmail.com, david@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, muchun.song@linux.dev, osalvador@suse.de, syzkaller-bugs@googlegroups.com, Lance Yang Subject: [PATCH 1/1] mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin Date: Mon, 10 Nov 2025 13:14:21 +0800 Message-ID: <20251110051421.29436-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Lance Yang The hugetlb VMA unmap path contains a potential deadlock, as reported by syzbot. In __hugetlb_zap_begin(), vma_lock is acquired before i_mmap_lock. This lock ordering conflicts with the page fault path in hugetlb_fault(), which acquires i_mmap_lock first, establishing the correct dependency as i_mmap_lock -> vma_lock. Chain exists of: &hugetlbfs_i_mmap_rwsem_key --> &hugetlb_fault_mutex_table[i] --> &vma_lock->rw_sema Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&vma_lock->rw_sema); lock(&hugetlb_fault_mutex_table[i]); lock(&vma_lock->rw_sema); lock(&hugetlbfs_i_mmap_rwsem_key); Resolve the deadlock by reordering the locks in __hugetlb_zap_begin() to follow the established i_mmap_lock -> vma_lock order. Reported-by: syzbot+3f5f9a0d292454409ca6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-mm/69113a97.a70a0220.22f260.00ca.GAE@google.com/ Signed-off-by: Lance Yang --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b1f47b87ae65..2719995af18e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5327,9 +5327,9 @@ void __hugetlb_zap_begin(struct vm_area_struct *vma, return; adjust_range_if_pmd_sharing_possible(vma, start, end); - hugetlb_vma_lock_write(vma); if (vma->vm_file) i_mmap_lock_write(vma->vm_file->f_mapping); + hugetlb_vma_lock_write(vma); } void __hugetlb_zap_end(struct vm_area_struct *vma, -- 2.49.0