From patchwork Mon Jan 18 11:34:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 366075 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55129C433DB for ; Mon, 18 Jan 2021 12:17:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D6CC221F0 for ; Mon, 18 Jan 2021 12:17:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391032AbhARMRb (ORCPT ); Mon, 18 Jan 2021 07:17:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:39146 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390880AbhARLqP (ORCPT ); Mon, 18 Jan 2021 06:46:15 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 53432222BB; Mon, 18 Jan 2021 11:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610970342; bh=SzQGuHebs9xocX/e/O6/CMMo8MrCd8y4OTB0WjxdZzE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bPBR5gv9Zf224eTVkL68EDrYw9pCkzXQsouThFY+WQqA0EtrLfb48aH6q8EBtiY9c 7aC5NR2gXRp8WB6dSi0+Wh/VdMC55zFnjInMpcphuRtxunvW4gLTVCDOANuB8gBjB7 Y3NYnx9Pon+Wo3SrO6VYYEZT4fSrmboOXyHsQfWg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Sasha Levin Subject: [PATCH 5.10 109/152] mm: fix clear_refs_write locking Date: Mon, 18 Jan 2021 12:34:44 +0100 Message-Id: <20210118113357.954800440@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210118113352.764293297@linuxfoundation.org> References: <20210118113352.764293297@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Linus Torvalds [ Upstream commit 29a951dfb3c3263c3a0f3bd9f7f2c2cfde4baedb ] Turning page table entries read-only requires the mmap_sem held for writing. So stop doing the odd games with turning things from read locks to write locks and back. Just get the write lock. Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/proc/task_mmu.c | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index ee5a235b30562..ab7d700b2caa4 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1215,41 +1215,26 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, .type = type, }; + if (mmap_write_lock_killable(mm)) { + count = -EINTR; + goto out_mm; + } if (type == CLEAR_REFS_MM_HIWATER_RSS) { - if (mmap_write_lock_killable(mm)) { - count = -EINTR; - goto out_mm; - } - /* * Writing 5 to /proc/pid/clear_refs resets the peak * resident set size to this mm's current rss value. */ reset_mm_hiwater_rss(mm); - mmap_write_unlock(mm); - goto out_mm; + goto out_unlock; } - if (mmap_read_lock_killable(mm)) { - count = -EINTR; - goto out_mm; - } tlb_gather_mmu(&tlb, mm, 0, -1); if (type == CLEAR_REFS_SOFT_DIRTY) { for (vma = mm->mmap; vma; vma = vma->vm_next) { if (!(vma->vm_flags & VM_SOFTDIRTY)) continue; - mmap_read_unlock(mm); - if (mmap_write_lock_killable(mm)) { - count = -EINTR; - goto out_mm; - } - for (vma = mm->mmap; vma; vma = vma->vm_next) { - vma->vm_flags &= ~VM_SOFTDIRTY; - vma_set_page_prot(vma); - } - mmap_write_downgrade(mm); - break; + vma->vm_flags &= ~VM_SOFTDIRTY; + vma_set_page_prot(vma); } mmu_notifier_range_init(&range, MMU_NOTIFY_SOFT_DIRTY, @@ -1261,7 +1246,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, if (type == CLEAR_REFS_SOFT_DIRTY) mmu_notifier_invalidate_range_end(&range); tlb_finish_mmu(&tlb, 0, -1); - mmap_read_unlock(mm); +out_unlock: + mmap_write_unlock(mm); out_mm: mmput(mm); }