From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 19E148F69 for ; Thu, 11 May 2023 12:59:12 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0E5AB1684; Thu, 11 May 2023 05:59:56 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 67D033F5A1; Thu, 11 May 2023 05:59:10 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , "Matthew Wilcox (Oracle)" , "Kirill A. Shutemov" , SeongJae Park Cc: Ryan Roberts , linux-kernel@vger.kernel.org, linux-mm@kvack.org, damon@lists.linux.dev Subject: [PATCH v1 3/5] mm: Fix failure to unmap pte on highmem systems Date: Thu, 11 May 2023 13:58:46 +0100 Message-Id: <20230511125848.78621-4-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230511125848.78621-1-ryan.roberts@arm.com> References: <20230511125848.78621-1-ryan.roberts@arm.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The loser of a race to service a pte for a device private entry in the swap path previously unlocked the ptl, but failed to unmap the pte. This only affects highmem systems since unmapping a pte is a noop on non-highmem systems. Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page") Signed-off-by: Ryan Roberts --- mm/memory.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index f69fbc251198..ed429e20a1bb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3728,10 +3728,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) vmf->page = pfn_swap_entry_to_page(entry); vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); - if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { - spin_unlock(vmf->ptl); - goto out; - } + if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) + goto unlock; /* * Get a page reference while we know the page can't be -- 2.25.1