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Wed, 17 Sep 2025 22:59:46 -0400 X-MC-Unique: Ki7YPC2oNNW4rsY61BHysA-1 X-Mimecast-MFC-AGG-ID: Ki7YPC2oNNW4rsY61BHysA_1758164384 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 970491800366; Thu, 18 Sep 2025 02:59:44 +0000 (UTC) Received: from localhost (unknown [10.72.112.180]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7B2A91800447; Thu, 18 Sep 2025 02:59:43 +0000 (UTC) Date: Thu, 18 Sep 2025 10:59:39 +0800 From: Baoquan He To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Andrew Morton , Michal Hocko , LKML , Michal Hocko Subject: Re: [PATCH v2 05/10] mm/vmalloc: Defer freeing partly initialized vm_struct Message-ID: References: <20250915134041.151462-1-urezki@gmail.com> <20250915134041.151462-6-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250915134041.151462-6-urezki@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Stat-Signature: s5xrrfz8pmckkq8cramnugpmk8iog67z X-Rspamd-Queue-Id: 06770C0004 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1758164387-281016 X-HE-Meta: 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 XhtB3lgJ 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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: On 09/15/25 at 03:40pm, Uladzislau Rezki (Sony) wrote: > __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(-) Reviewed-by: Baoquan He > > 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 >