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 24BCF2DE6E3; Mon, 20 Apr 2026 16:05:39 +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=1776701139; cv=none; b=NW8YAt+LBaCBZ1pViXgLBqP7PjP/Iwefx4Inpar6f1Zj/vzTSrOACgL5uiwwkQKgy0GZ8jW9j9Hmhp4tWUp6NM60p0uXWL27NzK5zvmCFhV5RiKLlUt4rOZyE08SxvUEBKfLIOMxfOenZWZ5AQKIhVo9w07VDvvhrimlHaI1GsQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776701139; c=relaxed/simple; bh=5kPyz8O3xTKsND1RTtJqOd1XvWnYVj3f3WVSGldaPfs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ewqcsZiiaQDRwD2DyCdsLQdFgp7IJem8M1FgBNMPKl6ZALeEBUvSvzHGfFau1+n+FzcehmxLmCs92rmRR8nvhsIZYMW2za3a17kPcQT1KCko/Q9FdpzwwB7z1GotYjluaEmJrrCHnMi+BeGQF70+jBNN4oOgZklnamsmpNXlGpI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HwOku7cT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HwOku7cT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87683C19425; Mon, 20 Apr 2026 16:05:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776701139; bh=5kPyz8O3xTKsND1RTtJqOd1XvWnYVj3f3WVSGldaPfs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HwOku7cTIb75VDefs6jW+CAKIwh8fpEKv1hjJJtdHc34hMwp9FGGFzq+BqOL7O8Yw V4Z1Fc9LhZv5ylqtW2MM227nRush2L6SSYJhFyLbFsOzTqhaXou/DlbotuzMrTGzBF qdNjfhP8JNbaIMcJP8ntdrD6tw5htutrHKFFkybs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jianhui Zhou , syzbot+f525fd79634858f478e7@syzkaller.appspotmail.com, SeongJae Park , "David Hildenbrand (Arm)" , "Mike Rapoport (Microsoft)" , Jane Chu , Andrea Arcangeli , Hugh Dickins , JonasZhou , Muchun Song , Oscar Salvador , Peter Xu , Sidhartha Kumar , Andrew Morton Subject: [PATCH 6.18 196/198] mm/userfaultfd: fix hugetlb fault mutex hash calculation Date: Mon, 20 Apr 2026 17:42:55 +0200 Message-ID: <20260420153942.673952978@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153935.605963767@linuxfoundation.org> References: <20260420153935.605963767@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jianhui Zhou commit 0217c7fb4de4a40cee667eb21901f3204effe5ac upstream. In mfill_atomic_hugetlb(), linear_page_index() is used to calculate the page index for hugetlb_fault_mutex_hash(). However, linear_page_index() returns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash() expects the index in huge page units. This mismatch means that different addresses within the same huge page can produce different hash values, leading to the use of different mutexes for the same huge page. This can cause races between faulting threads, which can corrupt the reservation map and trigger the BUG_ON in resv_map_release(). Fix this by introducing hugetlb_linear_page_index(), which returns the page index in huge page granularity, and using it in place of linear_page_index(). Link: https://lkml.kernel.org/r/20260310110526.335749-1-jianhuizzzzz@gmail.com Fixes: a08c7193e4f1 ("mm/filemap: remove hugetlb special casing in filemap.c") Signed-off-by: Jianhui Zhou Reported-by: syzbot+f525fd79634858f478e7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f525fd79634858f478e7 Acked-by: SeongJae Park Reviewed-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Cc: Jane Chu Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: JonasZhou Cc: Muchun Song Cc: Oscar Salvador Cc: Peter Xu Cc: SeongJae Park Cc: Sidhartha Kumar Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- include/linux/hugetlb.h | 17 +++++++++++++++++ mm/userfaultfd.c | 2 +- 2 files changed, 18 insertions(+), 1 deletion(-) --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -793,6 +793,23 @@ static inline unsigned huge_page_shift(s return h->order + PAGE_SHIFT; } +/** + * hugetlb_linear_page_index() - linear_page_index() but in hugetlb + * page size granularity. + * @vma: the hugetlb VMA + * @address: the virtual address within the VMA + * + * Return: the page offset within the mapping in huge page units. + */ +static inline pgoff_t hugetlb_linear_page_index(struct vm_area_struct *vma, + unsigned long address) +{ + struct hstate *h = hstate_vma(vma); + + return ((address - vma->vm_start) >> huge_page_shift(h)) + + (vma->vm_pgoff >> huge_page_order(h)); +} + static inline bool order_is_gigantic(unsigned int order) { return order > MAX_PAGE_ORDER; --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -569,7 +569,7 @@ retry: * in the case of shared pmds. fault mutex prevents * races with other faulting threads. */ - idx = linear_page_index(dst_vma, dst_addr); + idx = hugetlb_linear_page_index(dst_vma, dst_addr); mapping = dst_vma->vm_file->f_mapping; hash = hugetlb_fault_mutex_hash(mapping, idx); mutex_lock(&hugetlb_fault_mutex_table[hash]);