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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=TCOOE1SSD10QWz6ETDZQQa8vMzC3OQf7QgzVHTot3DF2mHh3BGpH6oizahN+4xoIw V3tUDGYYwfQVsmabwgFAkaDuZDnkhRAzjvVniXDXC3kgP/C7x4a0UowHWVHTmh4elc AprsIFNdFLJQcHPmZWalSfBqHNk4MvhSfNt4SVagQIekeLaWQy5pCgDAj7UMrU20Zu D3Uik2dp3cyRA39clPl+3cwOHuo3mg24zpfiZA9hCPtZfRLRbkFMFYgHLBhHzPK50r 8h7ykUxGXare4jcYCCOclmSEYI00dG8SFkpKA6pvK5xfrRa5Voib2AyqIlrEpk9+7c gkx+KmeMqrh+g== Date: Wed, 11 Nov 2026 13:30:38 +0000 From: "Lorenzo Stoakes (ARM)" To: Usama Arif Cc: Andrew Morton , apopple@nvidia.com, byungchul@sk.com, david@kernel.org, gourry@gourry.net, jannh@google.com, joshua.hahnjy@gmail.com, liam@infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.brost@intel.com, mhocko@suse.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, kas@kernel.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com, baolin.wang@linux.alibaba.com, Nico Pache , ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, stable@vger.kernel.org Subject: Re: [PATCH 3/3] fs/proc/task_mmu: account device-private PMDs as present in smaps Message-ID: References: <20261111113904.650722-1-usama.arif@linux.dev> <20261111113904.650722-4-usama.arif@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261111113904.650722-4-usama.arif@linux.dev> X-Stat-Signature: e94riejtqeu8ragociqysbecygdueoga X-Rspamd-Queue-Id: 76A1DA000C X-Rspam-User: X-Rspamd-Server: rspam11 X-Spam-Status: No, score=-15.8 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 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794403850-858686 X-HE-Meta: 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 uHWU4IcH sYeI76/FDUjNaN1ZOL7twzh4DgIzVDgB7BMqEOhGFXDEsE47fB1LZczJttPoxvYyiIqjnGOFSEHSoEjYf5oe+jCul5bZVMiUEZGfV1DkGxJ3ryFjaSIWta/VEHUguIPif3NfalQRe8FPYRrS3vF/A093BaA3QAgWyfyUunQ/TtrdOULDXt3W9emIJ9YKjxduZepznsvHYcWN3snf2RGLL1rc4BjR+Kb+bn7hEoBlw7WxKMhmqtJK/Xv+JbgE7+38kfkiwkAyDxVnQxXukG889o0A3f4/v1XHvhMLpGbWTj2++q+iPG0SjgWNM8NGZZrSqymVVcOeGnVu4nD/a9TdoU3UEop/RUKyoASk/f6n8WAp/s0bCKeOiUntRLWAdSBwZvC7jhh9CCqah/BE= 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 Wed, Nov 11, 2026 at 03:38:31AM -0800, Usama Arif wrote: > Device-private PMDs represent mapped pages, but smaps_pmd_entry() > passes present=false to smaps_account(). That treats them like migration > entries: mapcounts are ignored, PSS is charged in full, and exclusive > mappings are accounted as shared. > > Match smaps_pte_entry() and mark device-private PMDs as present so > smaps_account() uses mapcounts for PSS and private/shared accounting. > > Fixes: a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages") > Cc: stable@vger.kernel.org > Signed-off-by: Usama Arif It feels like PMD level device private entries have been the source of a lot of issues, maybe a good area to audit in general... :) Acked-by: Lorenzo Stoakes (ARM) > --- > fs/proc/task_mmu.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index c0d391186c2b8..ad97532fc1184 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -1032,8 +1032,11 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, > } else if (unlikely(thp_migration_supported())) { > const softleaf_t entry = softleaf_from_pmd(*pmd); > > - if (softleaf_has_pfn(entry)) > + if (softleaf_has_pfn(entry)) { > + if (softleaf_is_device_private(entry)) > + present = true; > page = softleaf_to_page(entry); > + } > } > if (IS_ERR_OR_NULL(page)) > return; > -- > 2.53.0-Meta > -- Cheers, Lorenzo