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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57BDDC6FA82 for ; Mon, 26 Sep 2022 16:15:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236512AbiIZQPb (ORCPT ); Mon, 26 Sep 2022 12:15:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236346AbiIZQPC (ORCPT ); Mon, 26 Sep 2022 12:15:02 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 061A6474C8; Mon, 26 Sep 2022 08:03:49 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id A52A71F37C; Mon, 26 Sep 2022 15:03:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1664204628; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=01qeiKj0xPZt2yV6W9R9BgcSaKJv5A3vVLXYXTwM4w8=; b=SA5M+y6N23TqcIqPGlbRc8oqT4Uuy+p5dMYFN6WK0NLkUGq8Jt47jRsNmOCMh7YcSh/8RF LCdmh9VcU3hX5sHLScUc+6omIv5MwG0GIJWHSlbv2lu2UkwbRQr2dOxIyoM0iIpUlhvr8/ QQkGXKB8V93LkmHWKWIjfY59ALczuio= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1664204628; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=01qeiKj0xPZt2yV6W9R9BgcSaKJv5A3vVLXYXTwM4w8=; b=bpEZ+jbhguY6P5sWORLAfxVIAwXXbwTT42WVUWUo9x1rPZv1LPnR+RQ5p4UbYjP3C5dwcW VCB47nBmhxhz4hDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 7071413486; Mon, 26 Sep 2022 15:03:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id HQsSGlS/MWOBGgAAMHmgww (envelope-from ); Mon, 26 Sep 2022 15:03:48 +0000 Message-ID: <76d0cb2b-a963-b867-4399-3e3c4828ecc4@suse.cz> Date: Mon, 26 Sep 2022 17:03:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH mm] mm: fix BUG with kvzalloc+GFP_ATOMIC Content-Language: en-US To: Uladzislau Rezki , Florian Westphal Cc: Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, Martin Zaharinov , Sebastian Andrzej Siewior References: <20220923103858.26729-1-fw@strlen.de> <20220923133512.GE22541@breakpoint.cc> <20220923145409.GF22541@breakpoint.cc> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On 9/23/22 17:10, Uladzislau Rezki wrote: > On Fri, Sep 23, 2022 at 04:54:09PM +0200, Florian Westphal wrote: >> Uladzislau Rezki wrote: >>> On Fri, Sep 23, 2022 at 03:35:12PM +0200, Florian Westphal wrote: >>>> Michal Hocko wrote: >>>>> On Fri 23-09-22 12:38:58, Florian Westphal wrote: >>>>>> Martin Zaharinov reports BUG() in mm land for 5.19.10 kernel: >>>>>> kernel BUG at mm/vmalloc.c:2437! >>>>>> invalid opcode: 0000 [#1] SMP >>>>>> CPU: 28 PID: 0 Comm: swapper/28 Tainted: G W O 5.19.9 #1 >>>>>> [..] >>>>>> RIP: 0010:__get_vm_area_node+0x120/0x130 >>>>>> __vmalloc_node_range+0x96/0x1e0 >>>>>> kvmalloc_node+0x92/0xb0 >>>>>> bucket_table_alloc.isra.0+0x47/0x140 >>>>>> rhashtable_try_insert+0x3a4/0x440 >>>>>> rhashtable_insert_slow+0x1b/0x30 >>>>>> [..] >>>>>> >>>>>> bucket_table_alloc uses kvzallocGPF_ATOMIC). If kmalloc fails, this now >>>>>> falls through to vmalloc and hits code paths that assume GFP_KERNEL. >>>>>> >>>>>> Revert the problematic change and stay with slab allocator. >>>>> >>>>> Why don't you simply fix the caller? >>>> >>>> Uh, not following? >>>> >>>> kvzalloc(GFP_ATOMIC) was perfectly fine, is this illegal again? >>>> >>> >>> static struct vm_struct *__get_vm_area_node(unsigned long size, >>> unsigned long align, unsigned long shift, unsigned long flags, >>> unsigned long start, unsigned long end, int node, >>> gfp_t gfp_mask, const void *caller) >>> { >>> struct vmap_area *va; >>> struct vm_struct *area; >>> unsigned long requested_size = size; >>> >>> BUG_ON(in_interrupt()); >>> ... >>> >>> >>> vmalloc is not supposed to be called from the IRQ context. >> >> It uses kvzalloc, not vmalloc api. >> >> Before 2018, rhashtable did use kzalloc OR kvzalloc, depending on gfp_t. >> >> Quote from 93f976b5190df327939 changelog: >> As of ce91f6ee5b3b ("mm: kvmalloc does not fallback to vmalloc for >> incompatible gfp flags") we can simplify the caller >> and trust kvzalloc() to just do the right thing. >> >> I fear that if this isn't allowed it will result in hard-to-spot bugs >> because things will work fine until a fallback to vmalloc happens. >> >> rhashtable may not be the only user of kvmalloc api that rely on >> ability to call it from (soft)irq. >> > Doing the "p = kmalloc(sizeof(*p), GFP_ATOMIC);" from an atomic context > is also a problem nowadays. Such code should be fixed across the kernel > because of PREEMPT_RT support. But the "atomic context" here is different, no? Calling kmalloc() from IRQ handlers AFAIK is ok as IRQ handlers are threaded on PREEMPT_RT. Calling it inside an local_irq_disable() would be a problem on the other hand. But then under e.g. spin_lock_irqsave() could be ok as those don't really disable irqs on RT. > -- > Uladzislau Rezki