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b=Z5W7jjZ5CHNgkF7jCfE0ZaOHYunaTI4LQaG+EZH2j9fRC+oGHMbSWTcm1ttSiCp1t SOW1jRzY1mB/gLSmMLe1CR6S8BG2H8gpsbHugwymJqUmLtl3nzZlWxhJKHxsws06Yr 7L4WjrVhRTcytnHcAuH5tC3+lr0RmYWw6sjmPzM1YPgUgIdLotSns9nMblv0aJ62YK JPsTZ6sjt9UJGMraJzXiOydmkTyx1O6/S0S9WiSUaXrhd1zeaxic7HhFT60Lj1A1TO S43KTJpl5if86/6JxeCR3njCW4UtLKv0UZ98hYyEhinG1EH90Ay3K5fT9cODSOvOrz RAmJBry2lrlXQ== Message-ID: <19012a9f-7a8d-4eb2-a441-cdb04184890b@kernel.org> Date: Fri, 30 Oct 2026 10:00:53 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv2] mm/huge_memory: set the mmu_gather page size in zap_huge_pud() To: "Ritesh Harjani (IBM)" , linux-mm@kvack.org, Andrew Morton Cc: Madhavan Srinivasan , Venkat Rao Bagalkote , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Muchun Song , Zi Yan , Baolin Wang , Pavithra References: <8b853e5f9f16145859407b28af654b0f79e12642.1793318297.git.ritesh.list@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: AB5C94000B X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: y8tabeam7o75xetkgwu8xqhmem85ywtd X-HE-Tag: 1793350861-319564 X-HE-Meta: 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 EgssavT/ 089X1mTAunr1kEWr3olFhFvFRG6gsdyGtIVVyNZtei4uBr1X3wEe3cwpFXyFQa1ql5TG21JcnMdro9dbB45fsGlRS//myGkYQ+tBt7huskxJJo+qm4crDar+woduzH9zg4maTk/N9ka3jEu7onuaHNPneVv+mVRoZxO5hLTdc0nFIRxxHk7djsrsQBjVUsUn6YTZu7wghSedEWDbSwhFxFjp73OiesGf24XFvguV2Y+0BcIP9Xr/uWEzc1lZpiY3Tq/OE2pGbN4sjkr4usWIHOwMf6w/9ddDKN1dUWhmO3ntGKSoSHFI9yYxJ3cutbTAOLDXcxUQN5WLUFs/mURJVHd0bVPJmRcbB+vQSgwozMAq5ET0x3bGqFPeF7vhFjayHCOk4M6yob8cNNvvGUWEiVpwZTle8sJXWmiX3Q9m4V50WkHcfJo8x4tY+QT+U6CnsFwuJcA5ut5PQQMYbk5mTWfYythMOXhrRjv8p 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 On 10/30/26 01:07, Ritesh Harjani (IBM) wrote: > Unmapping a device-dax mapping with 1G alignment on powerpc radix kernel > built with CONFIG_DEBUG_VM triggers this warning on every munmap: > > WARNING: mm/mmu_gather.c:176 at __tlb_remove_folio_pages_size+0x38/0x230 > NIP [c00000000063d508] __tlb_remove_folio_pages_size+0x38/0x230 > LR [c0000000006fb688] zap_huge_pud+0x1b8/0x2d0 > Call Trace: > zap_huge_pud+0x170/0x2d0 (unreliable) > __zap_vma_range+0x1604/0x1e20 > unmap_vmas+0xa0/0x1f0 > unmap_region+0xb0/0x130 > vms_complete_munmap_vmas+0x120/0x310 > do_vmi_align_munmap+0x1ec/0x240 > __vm_munmap+0x148/0x220 > sys_munmap+0x28/0x40 > > To trigger this - it is enough to mmap() /dev/dax0.0, touch the first > byte so that the whole 1G is mapped by a single PUD and then munmap() > it. > > PowerPC needs MMU_GATHER_PAGE_SIZE in which mmu_gather needs to record > the page size for which tlb flush is needed. zap_huge_pmd(), > zap_pte_range(), change_huge_pud() etc all do this already. However, > since commit: > dbe54153296d ("mm/huge_memory: add vmf_insert_folio_pud()") > > a device-dax PUD maps a real folio and zap_huge_pud() now hands it to > tlb_remove_page_size(tlb, page, HPAGE_PUD_SIZE). At that point > tlb->page_size is still whatever the previous user left behind, which is > 0 for the fresh gather set up by munmap() and so the check fires. > > Fix this in the same way like how other similar paths do. > > Fixes: dbe54153296d0 ("mm/huge_memory: add vmf_insert_folio_pud()") > Reported-by: Pavithra > Signed-off-by: Ritesh Harjani (IBM) > --- > [v1]->v2: > ========= > - Split the 2 part patch series. Patch-1 is now superseded by a different patch > from Muchun which he already posted [2]. > - No difference in this patch from v1. > > [v1]: https://lore.kernel.org/all/97f85592bb78a273be8519e6897e7f9b9bd31469.1793070429.git.ritesh.list@gmail.com/ > [2]: https://lore.kernel.org/all/20261029063601.1961415-1-songmuchun@bytedance.com/ > > mm/huge_memory.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index bd44d58e8684..7e589a2fb02d 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3040,6 +3040,8 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, > spinlock_t *ptl; > pud_t orig_pud; > > + tlb_change_page_size(tlb, HPAGE_PUD_SIZE); > + > ptl = __pud_trans_huge_lock(pud, vma); > if (!ptl) > return 0; > -- > 2.39.5 > Matches zap_huge_pmd(). I will wait a bit and then queue this shortly. This sounds like stable material? -- Cheers, David