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b=bbDjWhk/HrON7r5DDzIx0zRhSP31IG/7Z9RFLl5dyFRXh/sKuD42LRnSXT45yPJHe 3ZkGK/wJzIp/gz8R2jzr5SkoNMY/qbszU3v6vb3ISSiiGNtghSakPYAPDPxvw0hx2K fzendGOVPobWobrFQDpnvy9XRc3L/qAX80IYniQYVVJ7iNwIZTwgUdCfEqdIW0LAnf pe46xIVHomUN0FRTP9YpY4sAbwhZfBZVLgi+uHSmWrDLhT3TNgNMBBm91RnU196c3a yuQqyVVpUwBW4HER5FAAJjBCBZgrO0boOYDiTQ8I+kfnliJQiFzOZIwKeICoIDMNeE eMuHHGywQCavQ== From: "Vlastimil Babka (SUSE)" Date: Tue, 03 Nov 2026 17:16:49 +0100 Subject: [PATCH v2 3/5] mm: page_isolation: do not take slab pages for free X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261103-pgalloc-ai-hotfixes-v2-3-e0d2890ab74f@kernel.org> References: <20261103-pgalloc-ai-hotfixes-v2-0-e0d2890ab74f@kernel.org> In-Reply-To: <20261103-pgalloc-ai-hotfixes-v2-0-e0d2890ab74f@kernel.org> To: Johannes Weiner , "Gregory Price (Meta)" , Zi Yan , Shakeel Butt , Mike Rapoport , David Hildenbrand , Oscar Salvador , "Matthew Wilcox (Oracle)" Cc: Suren Baghdasaryan , Michal Hocko , Brendan Jackman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Vlastimil Babka (SUSE)" , Josef Bacik X-Mailer: b4 0.16.0 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9D4BF160002 X-Spam-Status: No, score=-18.8 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,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: is757183rcnqye6yjxdqyxrwtn63gxx5 X-HE-Tag: 1793722625-753506 X-HE-Meta: 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 eOnk1u6i xVZUWCvLFYzV0wJPY0aEn7XQl9W/uCHGYh/h8BhgH0mUV+aFqc68seBXpJlLDgVON6Ali+Dzya3JlBjPkYpVqHKz64hdF9IBDUyb1KnssrD1WAnhMYcuHwWOlc5nUvHHBb1htIVs0l2Etci2XQAysGJHvEIPud+9O9pXkHbQq7Mb86vwGyVWw32+AdNdvpIFtl+/F9gxP2xh3tcRDBLz/VxIdmHDwKuNN0YIciyudsxbD4U3QZchK9kAfc0WF7plPEz/eBTbW5Onr60ByG7V3ia44Ue25iCBUkWb9LdNoqcb0G8v4Xv2RWPXbZhtbs7WS0d3HT5a0UJUtDdwqOghDgfizjqqgfPlPH+AOqevIawrx1D89UErdRY/8HQ== 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 From: Josef Bacik page_is_unmovable() regards a page with a reference count of zero as free or about to be freed. Since slab allocates frozen pages, they will be wrongly considered to be freed if order 0 (higher-order compound pages are caught earlier). If such slabs are the only unmovable pages of a memory block, memory offlining now isolates the block, this can lead to offline_pages() looping without progress. Thus detect the slab pages as removable to return -EBUSY, as would happen before commit 9aec2fb0fd5e ("slab: allocate frozen pages"). Fixes: 9aec2fb0fd5e ("slab: allocate frozen pages") Assisted-by: LLM Signed-off-by: Josef Bacik Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Zi Yan Signed-off-by: Vlastimil Babka (SUSE) --- mm/memory_hotplug.c | 7 +++++++ mm/page_isolation.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c9cc42e54f05..0ab9a6e09222 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1832,6 +1832,13 @@ static int scan_movable_pages(unsigned long start, unsigned long end, if (PageOffline(page) && page_count(page)) return -EBUSY; + /* + * A page that was allocated, but was not a slab page yet, when + * its pageblock was isolated. + */ + if (PageSlab(page)) + return -EBUSY; + folio = page_folio(page); if (!folio_test_hugetlb(folio)) continue; diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 5aaad037384e..f4f0571607ab 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -74,6 +74,13 @@ bool page_is_unmovable(struct zone *zone, struct page *page, return false; } + /* + * Slab pages are frozen: do not take their reference count of zero + * for that of a free page. + */ + if (PageSlab(page)) + return true; + /* * We can't use page_count without pin a page * because another CPU can free compound page. -- 2.56.0