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Tue, 9 Apr 2024 19:24:56 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, cgroups@vger.kernel.org, linux-sh@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Peter Xu , Ryan Roberts , Yin Fengwei , Yang Shi , Zi Yan , Jonathan Corbet , Hugh Dickins , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Chris Zankel , Max Filippov , Muchun Song , Miaohe Lin , Naoya Horiguchi , Richard Chang Subject: [PATCH v1 08/18] mm/huge_memory: use folio_mapcount() in zap_huge_pmd() sanity check Date: Tue, 9 Apr 2024 21:22:51 +0200 Message-ID: <20240409192301.907377-9-david@redhat.com> In-Reply-To: <20240409192301.907377-1-david@redhat.com> References: <20240409192301.907377-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1662F40013 X-Stat-Signature: qjh6471fs19yrhz7bfwd3p96auhwupjg X-Rspam-User: X-HE-Tag: 1712690718-271124 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: We want to limit the use of page_mapcount() to the places where it is absolutely necessary. Let's similarly check for folio_mapcount() underflows instead of page_mapcount() underflows like we do in zap_present_folio_ptes() now. Instead of the VM_BUG_ON(), we should actually be doing something like print_bad_pte(). For now, let's keep it simple and use WARN_ON_ONCE(), performing that check independently of DEBUG_VM. Signed-off-by: David Hildenbrand --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d8d2ed80b0bf..68ac27d229ef 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1851,7 +1851,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, folio = page_folio(page); folio_remove_rmap_pmd(folio, page, vma); - VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); + WARN_ON_ONCE(folio_mapcount(folio) < 0); VM_BUG_ON_PAGE(!PageHead(page), page); } else if (thp_migration_supported()) { swp_entry_t entry;