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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95F3DC6FD1D for ; Tue, 21 Mar 2023 07:05:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 04A566B0075; Tue, 21 Mar 2023 03:05:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F3C136B0078; Tue, 21 Mar 2023 03:05:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E2A616B007B; Tue, 21 Mar 2023 03:05:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D68AB6B0075 for ; Tue, 21 Mar 2023 03:05:04 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6C0B8160F6F for ; Tue, 21 Mar 2023 07:05:04 +0000 (UTC) X-FDA: 80592018528.03.3552842 Received: from out-51.mta1.migadu.com (out-51.mta1.migadu.com [95.215.58.51]) by imf06.hostedemail.com (Postfix) with ESMTP id 75A2818001A for ; Tue, 21 Mar 2023 07:05:01 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=CJL06fy9; spf=pass (imf06.hostedemail.com: domain of muchun.song@linux.dev designates 95.215.58.51 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1679382301; h=from:from:sender:reply-to:subject:subject: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:dkim-signature; bh=+McZTV1kAS70sseCFB9E43G9HETXQ3b8ag52JbteiD0=; b=KTmnk7sax/nAkuaqC2+PU9/SN1iGXl7xOHe9CPOZ6iV6QG2XzxdlcJnwEngRq2IXEOEnba FXrXEVt0FAgxof25MUBjnZwXuPjmV4w4bXpGRleJCJ9O8Xi+glAVl9+Xxlq241nt80tzf3 uj1dM5bq5pm4PpSCGXXIIXtjs/xNIPE= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=CJL06fy9; spf=pass (imf06.hostedemail.com: domain of muchun.song@linux.dev designates 95.215.58.51 as permitted sender) smtp.mailfrom=muchun.song@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1679382301; a=rsa-sha256; cv=none; b=1Z4gf1ATIJNUbwJFR3VD6gzOsceNhpeiSZyko/aDALaaszhFtAxGhqcDUVAhhQ52GxwlD6 esLLzOcQOcLiqh4aslkOK8VQgDPcaudavLvWq00uetOdEAXVCoBboPn+2cZC00Q+2Rt4lQ Re8HkbQtSDktu4cTpePEnVpFmgoYLl4= Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1679382299; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+McZTV1kAS70sseCFB9E43G9HETXQ3b8ag52JbteiD0=; b=CJL06fy9Y/XNtRhQXe1npEGcF1jFne3go0w6cCUnG7ZySGZtj8jkIWiMXOiMlNC1gWEP9f fR1vAOULQZrNyar2EDI+qg5PsTB9vKe6mP4Es8h4IzlElQAI209GZcBkFuSWRiZ9O2QLQw /YQngQDOs65kiseKrpdVlavJoQUSVls= Date: Tue, 21 Mar 2023 15:04:46 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] mm: kfence: fix PG_slab and memcg_data clearing To: Peng Zhang Cc: kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dvyukov@google.com, roman.gushchin@linux.dev, jannh@google.com, sjpark@amazon.de, akpm@linux-foundation.org, elver@google.com, glider@google.com, Muchun Song References: <20230320030059.20189-1-songmuchun@bytedance.com> <974ef73e-ab4f-7b24-d070-c981654e8c22@bytedance.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <974ef73e-ab4f-7b24-d070-c981654e8c22@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 75A2818001A X-Stat-Signature: 39q8m4as8zi4jrrst31ppod597zxntb3 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1679382301-571367 X-HE-Meta: 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 e2rMRkzV fTX2ORtV4g5Hd2/kQupcJE1advGT2WxBOsSVt7HG4v+Zs8cwD6xBcVTCs3uI5Z9u2f4dZ52uekOxSkcYsd5PcOdJdFRSSPwlLIkVBQdLmkqnB/TWkhLbt91aY6sIlKOyf3CZ9VzwXJD7komFC+ISvhJhJLnqn2C1XYk79VRx3FqAZJhSw6Pr70qGoryndKny00umMIy0ks9Kz4umWIw4KmZ8KdwNsVuGWYQJbebkimrujVlWy6XexCZXxmAYj+wFkFVS9 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 2023/3/21 12:14, Peng Zhang wrote: > > 在 2023/3/20 11:00, Muchun Song 写道: >> It does not reset PG_slab and memcg_data when KFENCE fails to initialize >> kfence pool at runtime. It is reporting a "Bad page state" message when >> kfence pool is freed to buddy. The checking of whether it is a compound >> head page seems unnecessary sicne we already guarantee this when >> allocating >> kfence pool, removing the check to simplify the code. >> >> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") >> Fixes: 8f0b36497303 ("mm: kfence: fix objcgs vector allocation") >> Signed-off-by: Muchun Song >> --- >>   mm/kfence/core.c | 30 +++++++++++++++--------------- >>   1 file changed, 15 insertions(+), 15 deletions(-) >> >> diff --git a/mm/kfence/core.c b/mm/kfence/core.c >> index 79c94ee55f97..d66092dd187c 100644 >> --- a/mm/kfence/core.c >> +++ b/mm/kfence/core.c >> @@ -561,10 +561,6 @@ static unsigned long kfence_init_pool(void) >>           if (!i || (i % 2)) >>               continue; >>   -        /* Verify we do not have a compound head page. */ >> -        if (WARN_ON(compound_head(&pages[i]) != &pages[i])) >> -            return addr; >> - >>           __folio_set_slab(slab_folio(slab)); >>   #ifdef CONFIG_MEMCG >>           slab->memcg_data = (unsigned long)&kfence_metadata[i / 2 - >> 1].objcg | >> @@ -597,12 +593,26 @@ static unsigned long kfence_init_pool(void) >>             /* Protect the right redzone. */ >>           if (unlikely(!kfence_protect(addr + PAGE_SIZE))) >> -            return addr; >> +            goto reset_slab; >>             addr += 2 * PAGE_SIZE; >>       } >>         return 0; >> + >> +reset_slab: >> +    for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { >> +        struct slab *slab = page_slab(&pages[i]); >> + >> +        if (!i || (i % 2)) >> +            continue; >> +#ifdef CONFIG_MEMCG >> +        slab->memcg_data = 0; >> +#endif >> +        __folio_clear_slab(slab_folio(slab)); >> +    } > Can this loop be simplified to this? > >     for (i = 2; i < KFENCE_POOL_SIZE / PAGE_SIZE; i+=2) { >         struct slab *slab = page_slab(&pages[i]); > #ifdef CONFIG_MEMCG >         slab->memcg_data = 0; > #endif >         __folio_clear_slab(slab_folio(slab)); >     } > It's a good simplification. The loop setting Pg_slab before this also can be simplified in the same way. However, I choose a consistent way to fix this bug. I'd like to send a separate simplification patch to simplify both two loops instead of in a bugfix patch. Thanks.