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 70C1F8801; Tue, 30 Apr 2024 11:11:30 +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=1714475490; cv=none; b=qCETvDiWncTDwVRSF8Nqk29AWbK2AMVR7aYKfiIlJntexvhlmf4EIXUhkuYXZRGRl+sUZxBwBYTon/BGxHiE5fJI7I/DnOvnOXl552iqCVHfs2fbFpIWXDHnQTyftGXzATNkQmltYCytWVCg8kfG0dH1P7FG8no/GviYRNiPKX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714475490; c=relaxed/simple; bh=Ak2rZDxDOqze2OA7sGtfRJ1rQuuYPdFxNl/68+UAGb4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q77WoZC0+naH/pknMpSPUN+nB8ZtlKzAU1f3NVvFe4pNbNIM4taoQgbjS45ODF4/JDqlLcHfVU4LKrumr7fqIN1pb35hws4ymxROjUNYXrO3hvh76hrcb2pkgW9LhIvyXD2okQBzTc5CO5gnDyDN+PW3lngXz6GARloMiJ/8u6w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PChNFFQf; 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="PChNFFQf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A482CC4AF19; Tue, 30 Apr 2024 11:11:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1714475490; bh=Ak2rZDxDOqze2OA7sGtfRJ1rQuuYPdFxNl/68+UAGb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PChNFFQf+raGh0E6qfMr9V+ImtUbQ0e9B5+QvJx4rvgKID7PSkNI73V+D/8VsE5BR bxbsWRTiQHj2xmUFwd0IOCpSXXjFin+x+bN7Jv5busbu/xMHiE05a2PvK8fP6z7MrP 532yEc6kq+N/cwmTGTUyvphCCNTRKPmFIt2heTj8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Miaohe Lin , Thorvald Natvig , Jane Chu , Christian Brauner , Heiko Carstens , Kent Overstreet , "Liam R. Howlett" , Mateusz Guzik , "Matthew Wilcox (Oracle)" , Muchun Song , Oleg Nesterov , Peng Zhang , Tycho Andersen , Andrew Morton Subject: [PATCH 6.6 110/186] fork: defer linking file vma until vma is fully initialized Date: Tue, 30 Apr 2024 12:39:22 +0200 Message-ID: <20240430103101.226378191@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240430103058.010791820@linuxfoundation.org> References: <20240430103058.010791820@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miaohe Lin commit 35e351780fa9d8240dd6f7e4f245f9ea37e96c19 upstream. Thorvald reported a WARNING [1]. And the root cause is below race: CPU 1 CPU 2 fork hugetlbfs_fallocate dup_mmap hugetlbfs_punch_hole i_mmap_lock_write(mapping); vma_interval_tree_insert_after -- Child vma is visible through i_mmap tree. i_mmap_unlock_write(mapping); hugetlb_dup_vma_private -- Clear vma_lock outside i_mmap_rwsem! i_mmap_lock_write(mapping); hugetlb_vmdelete_list vma_interval_tree_foreach hugetlb_vma_trylock_write -- Vma_lock is cleared. tmp->vm_ops->open -- Alloc new vma_lock outside i_mmap_rwsem! hugetlb_vma_unlock_write -- Vma_lock is assigned!!! i_mmap_unlock_write(mapping); hugetlb_dup_vma_private() and hugetlb_vm_op_open() are called outside i_mmap_rwsem lock while vma lock can be used in the same time. Fix this by deferring linking file vma until vma is fully initialized. Those vmas should be initialized first before they can be used. Link: https://lkml.kernel.org/r/20240410091441.3539905-1-linmiaohe@huawei.com Fixes: 8d9bfb260814 ("hugetlb: add vma based lock for pmd sharing") Signed-off-by: Miaohe Lin Reported-by: Thorvald Natvig Closes: https://lore.kernel.org/linux-mm/20240129161735.6gmjsswx62o4pbja@revolver/T/ [1] Reviewed-by: Jane Chu Cc: Christian Brauner Cc: Heiko Carstens Cc: Kent Overstreet Cc: Liam R. Howlett Cc: Mateusz Guzik Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Muchun Song Cc: Oleg Nesterov Cc: Peng Zhang Cc: Tycho Andersen Cc: Signed-off-by: Andrew Morton Signed-off-by: Miaohe Lin Signed-off-by: Greg Kroah-Hartman --- kernel/fork.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -727,6 +727,15 @@ static __latent_entropy int dup_mmap(str } else if (anon_vma_fork(tmp, mpnt)) goto fail_nomem_anon_vma_fork; vm_flags_clear(tmp, VM_LOCKED_MASK); + /* + * Copy/update hugetlb private vma information. + */ + if (is_vm_hugetlb_page(tmp)) + hugetlb_dup_vma_private(tmp); + + if (tmp->vm_ops && tmp->vm_ops->open) + tmp->vm_ops->open(tmp); + file = tmp->vm_file; if (file) { struct address_space *mapping = file->f_mapping; @@ -743,12 +752,6 @@ static __latent_entropy int dup_mmap(str i_mmap_unlock_write(mapping); } - /* - * Copy/update hugetlb private vma information. - */ - if (is_vm_hugetlb_page(tmp)) - hugetlb_dup_vma_private(tmp); - /* Link the vma into the MT */ if (vma_iter_bulk_store(&vmi, tmp)) goto fail_nomem_vmi_store; @@ -757,9 +760,6 @@ static __latent_entropy int dup_mmap(str if (!(tmp->vm_flags & VM_WIPEONFORK)) retval = copy_page_range(tmp, mpnt); - if (tmp->vm_ops && tmp->vm_ops->open) - tmp->vm_ops->open(tmp); - if (retval) goto loop_out; }