From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DA921E1A17 for ; Thu, 18 Sep 2025 02:59:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758164392; cv=none; b=mu9LOX3bm8rNS93AvwhuNTzD9uBZyRc6zeUfXo5VLtC6uIpQddNlwWYqv8VunXi9QcpIVTUQ+ThBxrb4Or1h/+KdsSlTfAmyTxfv3pNY8hpB6LzKz5kPMHyfk4ZgI9hQrvf5If1yfw2VUIvsRKmJvZ7FVB15SQ79IlF1Re7pFgI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758164392; c=relaxed/simple; bh=IRvSw2Dx3BviezEMqUHIj7NKGUdxC/8LoBdFA3kIPKM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=C7toMz+Zc/HF5DrkXHXBJrbhfxBBz6xafhc8UNUil8P5Re5fHrKz3tw0/Zqy4LZFfZ+on2/ktyam2z6cb7KxbSR6qKszteqHiJBnDTbaXfovwNqPuepLdAdcgIITB7IjnmyDHYFUHgUJB7pbeWnZIXp3/0S4/XLz5ZKWeY1DShQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KQS7kXDu; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KQS7kXDu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758164389; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OcKW5Vz9+O4NXqO35+tX18KtIiANJDc+I7FuiS+m58c=; b=KQS7kXDu55Hb4wh9ITY4xrOcPnCJA/m8XJ28XXu/bNJX3xHsPsugJDOXXgxEtUBLzxLGhF vI8lHyLd9pKCba9wJNoS7Ra6vt8It2lJrwrnL1w+/jSPS/mAumJKPWd8xXBvH0r8gRVluz 5PhPzu/MbMhCJp/0YR6gMOzVwllWJWw= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-553-Ki7YPC2oNNW4rsY61BHysA-1; 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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 >