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([2a09:bac6:37a8:1f19::319:116]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47f864305f5sm30334154f8f.17.2026.07.25.03.14.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 25 Jul 2026 03:14:22 -0700 (PDT) From: Matt Fleming To: Andrew Morton Cc: David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Dave Chinner , Qi Zheng , Roman Gushchin , Muchun Song , Kairui Song , Shakeel Butt , Matthew Wilcox , syzbot+c5b060ce82921a2fd500@syzkaller.appspotmail.com, stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com, Matt Fleming Subject: [PATCH v2] mm/huge_memory: Initialise workingset state before folio split Date: Sat, 25 Jul 2026 11:14:19 +0100 Message-ID: <20260725101419.3938406-1-matt@readmodwrite.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Matt Fleming xas_try_split() adds __GFP_ACCOUNT for page-cache xa_nodes, but __folio_split() leaves the xa_state's xa_lru unset. That lets a live, memcg-charged xa_node exist without being linked into the mapping's shadow_nodes list_lru; when reclaim later walks the list_lru it trips VM_WARN_ON(!css_is_dying()). Use mapping_set_update() to install both the workingset update callback and the shadow_nodes list_lru on the xa_state. Reported-by: syzbot+c5b060ce82921a2fd500@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c5b060ce82921a2fd500 Fixes: 58729c04cf10 ("mm/huge_memory: add buddy allocator like (non-uniform) folio_split()") Cc: stable@vger.kernel.org Reviewed-by: Zi Yan Signed-off-by: Matt Fleming --- Changes in v2: - Move mapping_set_update() after filemap_release_folio() succeeds. - Add Zi Yan's Reviewed-by. Link: https://lore.kernel.org/linux-mm/20260724195244.3715130-1-matt@readmodwrite.com/ --- mm/huge_memory.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b5d1e9d4463d..4ddbc72e92fd 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -4033,7 +4033,7 @@ static int __folio_split(struct folio *folio, unsigned int new_order, gfp_t gfp; mapping = folio->mapping; - min_order = mapping_min_folio_order(folio->mapping); + min_order = mapping_min_folio_order(mapping); if (new_order < min_order) { ret = -EINVAL; goto out; @@ -4047,6 +4047,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order, goto out; } + mapping_set_update(&xas, mapping); + if (split_type == SPLIT_TYPE_UNIFORM) { xas_set_order(&xas, folio->index, new_order); xas_split_alloc(&xas, folio, old_order, gfp); -- 2.43.0