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Thu, 07 Aug 2025 00:58:17 -0700 (PDT) Received: from pc638.lan ([2001:9b1:d5a0:a500:2d8:61ff:fec9:d743]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-55b88c9b1fesm2501995e87.96.2025.08.07.00.58.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Aug 2025 00:58:17 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: linux-mm@kvack.org, Andrew Morton Cc: Vlastimil Babka , Michal Hocko , Baoquan He , LKML , Uladzislau Rezki Subject: [PATCH 6/8] mm/vmalloc: Defer freeing partly initialized vm_struct Date: Thu, 7 Aug 2025 09:58:08 +0200 Message-Id: <20250807075810.358714-7-urezki@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250807075810.358714-1-urezki@gmail.com> References: <20250807075810.358714-1-urezki@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: F0522A000C X-Stat-Signature: pxnwqmeytkk7ch1g6itt59q6puncqo1p X-Rspam-User: X-HE-Tag: 1754553499-5339 X-HE-Meta: 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 RPZRYlWg 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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: __vmalloc_area_node() may call free_vmap_area() or vfree() on error paths, both of which can sleep. This becomes problematic if the function is invoked from an atomic context, such as when GFP_ATOMIC or GFP_NOWAIT is passed via gfp_mask. To fix this, unify error paths and defer the cleanup of partly initialized vm_struct objects to a workqueue. This ensures that freeing happens in a process context and avoids invalid sleeps in atomic regions. Signed-off-by: Uladzislau Rezki (Sony) --- include/linux/vmalloc.h | 6 +++++- mm/vmalloc.c | 34 +++++++++++++++++++++++++++++++--- 2 files changed, 36 insertions(+), 4 deletions(-) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index fdc9aeb74a44..b1425fae8cbf 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -50,7 +50,11 @@ struct iov_iter; /* in uio.h */ #endif struct vm_struct { - struct vm_struct *next; + union { + struct vm_struct *next; /* Early registration of vm_areas. */ + struct llist_node llnode; /* Asynchronous freeing on error paths. */ + }; + void *addr; unsigned long size; unsigned long flags; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 7f48a54ec108..2424f80d524a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3680,6 +3680,35 @@ vm_area_alloc_pages(gfp_t gfp, int nid, return nr_allocated; } +static LLIST_HEAD(pending_vm_area_cleanup); +static void cleanup_vm_area_work(struct work_struct *work) +{ + struct vm_struct *area, *tmp; + struct llist_node *head; + + head = llist_del_all(&pending_vm_area_cleanup); + if (!head) + return; + + llist_for_each_entry_safe(area, tmp, head, llnode) { + if (!area->pages) + free_vm_area(area); + else + vfree(area->addr); + } +} + +/* + * Helper for __vmalloc_area_node() to defer cleanup + * of partially initialized vm_struct in error paths. + */ +static DECLARE_WORK(cleanup_vm_area, cleanup_vm_area_work); +static void defer_vm_area_cleanup(struct vm_struct *area) +{ + if (llist_add(&area->llnode, &pending_vm_area_cleanup)) + schedule_work(&cleanup_vm_area); +} + static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot, unsigned int page_shift, int node) @@ -3711,8 +3740,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, warn_alloc(gfp_mask, NULL, "vmalloc error: size %lu, failed to allocated page array size %lu", nr_small_pages * PAGE_SIZE, array_size); - free_vm_area(area); - return NULL; + goto fail; } set_vm_area_page_order(area, page_shift - PAGE_SHIFT); @@ -3789,7 +3817,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, return area->addr; fail: - vfree(area->addr); + defer_vm_area_cleanup(area); return NULL; } -- 2.39.5