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Mon, 15 Sep 2025 06:40:47 -0700 (PDT) Received: from localhost.localdomain ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-573c8330e54sm1150719e87.63.2025.09.15.06.40.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Sep 2025 06:40:46 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: linux-mm@kvack.org, Andrew Morton Cc: Michal Hocko , Baoquan He , LKML , Uladzislau Rezki , Michal Hocko Subject: [PATCH v2 05/10] mm/vmalloc: Defer freeing partly initialized vm_struct Date: Mon, 15 Sep 2025 15:40:35 +0200 Message-ID: <20250915134041.151462-6-urezki@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250915134041.151462-1-urezki@gmail.com> References: <20250915134041.151462-1-urezki@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 73AF1160016 X-Stat-Signature: u5htcbmmifk7qshd6f15w9x6qc46abp4 X-Rspam-User: X-HE-Tag: 1757943649-893941 X-HE-Meta: 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 WndUtNQT 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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. Acked-by: Michal Hocko 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 2759dac6be44..97252078a3dc 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 b77e8be75f10..e61e62872372 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3686,6 +3686,35 @@ 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) @@ -3717,8 +3746,7 @@ 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); @@ -3795,7 +3823,7 @@ 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; } -- 2.47.3