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Tue, 10 Nov 2026 08:23:12 -0800 (PST) Date: Tue, 10 Nov 2026 08:23:11 -0800 From: Breno Leitao To: "Kiryl Shutsemau (Meta)" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lorenzo Stoakes , Mike Rapoport , David Hildenbrand , stable@vger.kernel.org, Sashiko AI review , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Muhammad Usama Anjum , Stephen Rothwell , Arnd Bergmann , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 1/6] fs/proc/task_mmu: fix make_uffd_wp_huge_pte() prot-update race Message-ID: References: <20260529172331.356655-1-kas@kernel.org> <20260529172331.356655-2-kas@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260529172331.356655-2-kas@kernel.org> X-Rspamd-Server: rspam06 X-Stat-Signature: 6453su9tazsth13x31c8frjgifxa9kxr X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: B28721C0009 X-Rspam-User: X-HE-Tag: 1794327793-276330 X-HE-Meta: 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 FtTGKqcI 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Hello Kiryl, On Fri, May 29, 2026 at 06:23:25PM +0100, Kiryl Shutsemau (Meta) wrote: > The non-hugetlb sibling make_uffd_wp_pte() does this correctly via > ptep_modify_prot_start() / ptep_modify_prot_commit(). Mirror that > pattern for the present-PTE branch. The migration case stays as-is -- > migration entries are non-present, so there's no hardware update to > race against. I am seeing this on next-20261109 (arm64, PAGE_TABLE_CHECK) while the pagemap_ioctl kselftest runs next to a workload that migrates pages: WARNING: mm/page_table_check.c:206 at __page_table_check_ptes_set+0x168/0x178, CPU#21: pagemap_ioctl/894691 Call trace: __page_table_check_ptes_set+0x168/0x178 (P) __set_ptes_anysz+0x50/0x240 make_uffd_wp_pte+0x104/0x1c8 pagemap_scan_pmd_entry+0x1b98/0x1df8 walk_pgd_range+0x7b4/0xd00 __walk_page_range+0x108/0x510 walk_page_range_mm_unsafe+0x150/0x3e8 do_pagemap_cmd+0x418/0x7d0 __arm64_sys_ioctl+0xc08/0x1338 given you've touched this recently, I am wondering if you've seen it. --breno