From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E411C43215 for ; Sat, 30 Nov 2019 23:09:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E39E22231B for ; Sat, 30 Nov 2019 23:09:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1ZdZyFhw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E39E22231B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7D3246B0003; Sat, 30 Nov 2019 18:09:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 75CBF6B0005; Sat, 30 Nov 2019 18:09:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 623B86B0006; Sat, 30 Nov 2019 18:09:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0178.hostedemail.com [216.40.44.178]) by kanga.kvack.org (Postfix) with ESMTP id 487166B0003 for ; Sat, 30 Nov 2019 18:09:11 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id F2C7E181AEF09 for ; Sat, 30 Nov 2019 23:09:10 +0000 (UTC) X-FDA: 76214486460.18.magic59_330270433e602 X-HE-Tag: magic59_330270433e602 X-Filterd-Recvd-Size: 4624 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Sat, 30 Nov 2019 23:09:10 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4245C2072C; Sat, 30 Nov 2019 23:09:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575155349; bh=+rUlFwPAJgYEfS8TYww8cNCIY3tqU3ON5emEPe+Dxfg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1ZdZyFhwrZJBqdGQXkp6Hoijogl30uQ+ZRQwlJf19mnxuMjE5ivT9r0jE3o+EiZp0 BT4uDPgEM32KfQwXAFwS1mhENhRHgOiIMtV/bNx7AVvIAS7OZwYtI+3R6NYm5QxwIQ M0q50569YvYKbV7UK+jtko15zqW0G9piez2yGHOU= Date: Sat, 30 Nov 2019 15:09:08 -0800 From: Andrew Morton To: Christopher Lameter Cc: Yu Zhao , Pekka Enberg , David Rientjes , Joonsoo Kim , "Kirill A . Shutemov" , Tetsuo Handa , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" Subject: Re: [FIX] slub: Remove kmalloc under list_lock from list_slab_objects() V2 Message-Id: <20191130150908.06b2646edfa7bdc12a943c25@linux-foundation.org> In-Reply-To: References: <20190914000743.182739-1-yuzhao@google.com> <20191108193958.205102-1-yuzhao@google.com> <20191108193958.205102-2-yuzhao@google.com> <20191109230147.GA75074@google.com> <20191110184721.GA171640@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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: On Mon, 11 Nov 2019 15:55:05 +0000 (UTC) Christopher Lameter wrote: > Regardless of the issue with memcgs allowing allocations from its > kmalloc array during shutdown: This patch cleans things up and properly > allocates the bitmap outside of the list_lock. > > > [FIX] slub: Remove kmalloc under list_lock from list_slab_objects() V2 > > V1->V2 : Properly handle CONFIG_SLUB_DEBUG. Handle bitmap free correctly. > > list_slab_objects() is called when a slab is destroyed and there are objects still left > to list the objects in the syslog. This is a pretty rare event. > > And there it seems we take the list_lock and call kmalloc while holding that lock. > > Perform the allocation in free_partial() before the list_lock is taken. No response here? It looks a lot simpler than the originally proposed patch? > --- linux.orig/mm/slub.c 2019-10-15 13:54:57.032655296 +0000 > +++ linux/mm/slub.c 2019-11-11 15:52:11.616397853 +0000 > @@ -3690,14 +3690,15 @@ error: > } > > static void list_slab_objects(struct kmem_cache *s, struct page *page, > - const char *text) > + const char *text, unsigned long *map) > { > #ifdef CONFIG_SLUB_DEBUG > void *addr = page_address(page); > void *p; > - unsigned long *map = bitmap_zalloc(page->objects, GFP_ATOMIC); > + > if (!map) > return; > + > slab_err(s, page, text, s->name); > slab_lock(page); > > @@ -3710,7 +3711,6 @@ static void list_slab_objects(struct kme > } > } > slab_unlock(page); > - bitmap_free(map); > #endif > } > > @@ -3723,6 +3723,11 @@ static void free_partial(struct kmem_cac > { > LIST_HEAD(discard); > struct page *page, *h; > + unsigned long *map = NULL; > + > +#ifdef CONFIG_SLUB_DEBUG > + map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL); > +#endif > > BUG_ON(irqs_disabled()); > spin_lock_irq(&n->list_lock); > @@ -3732,11 +3737,16 @@ static void free_partial(struct kmem_cac > list_add(&page->slab_list, &discard); > } else { > list_slab_objects(s, page, > - "Objects remaining in %s on __kmem_cache_shutdown()"); > + "Objects remaining in %s on __kmem_cache_shutdown()", > + map); > } > } > spin_unlock_irq(&n->list_lock); > > +#ifdef CONFIG_SLUB_DEBUG > + bitmap_free(map); > +#endif > + > list_for_each_entry_safe(page, h, &discard, slab_list) > discard_slab(s, page); > }