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TO_DN_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: On 10/16/25 15:09, Harry Yoo wrote: >> ----8<---- >> From 8151384e5baf34db5812ed51e2e463796ab6e973 Mon Sep 17 00:00:00 2001 >> From: Hao Ge >> Date: Wed, 15 Oct 2025 22:16:42 +0800 >> Subject: [PATCH] slab: reset slab->obj_ext when freeing and it is >> OBJEXTS_ALLOC_FAIL >> >> If obj_exts allocation failed, slab->obj_exts is set to OBJEXTS_ALLOC_FAIL, >> But we do not clear it when freeing the slab. Since OBJEXTS_ALLOC_FAIL and >> MEMCG_DATA_OBJEXTS currently share the same bit position, during the >> release of the associated folio, > >> a VM_BUG_ON_FOLIO() check in >> folio_memcg_kmem() is triggered because it was mistakenly assumed that >> a valid folio->memcg_data was not cleared before freeing the folio. > > nit: maybe this can be massaged as "a VM_BUG_ON_FOLIO() check in folio_memcg_kmem() > is triggered because the OBJEXTS_ALLOC_FAIL flag was not cleared, > causing it to be interpreted as a kmem folio (non-slab) with > MEMCG_OBJEXTS_DATA flag set, which is invalid because MEMCG_OBJEXTS_DATA > is supposed to be set only on slabs." Thanks, applied >> Another problem that predates sharing the OBJEXTS_ALLOC_FAIL and >> MEMCG_DATA_OBJEXTS bits is that on configurations with >> is_check_pages_enabled(), the non-cleared bit in page->memcg_data will >> trigger a free_page_is_bad() failure "page still charged to cgroup" >> >> When freeing a slab, we clear slab->obj_exts if the obj_ext array has >> been successfully allocated. So let's clear it also when the allocation >> has failed. >> >> Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations") >> Link: https://lore.kernel.org/all/20251015141642.700170-1-hao.ge@linux.dev/ >> Cc: >> Signed-off-by: Hao Ge >> Signed-off-by: Vlastimil Babka >> --- > > Looks good to me, > Reviewed-by: Harry Yoo and this too.