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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 C41DFC2D0EA for ; Wed, 8 Apr 2020 15:32:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 844F1206F7 for ; Wed, 8 Apr 2020 15:32:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=soleen.com header.i=@soleen.com header.b="Ph6oKMMT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 844F1206F7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=soleen.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 17C5F8E000D; Wed, 8 Apr 2020 11:32:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 12DE78E0006; Wed, 8 Apr 2020 11:32:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0430E8E000D; Wed, 8 Apr 2020 11:32:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0242.hostedemail.com [216.40.44.242]) by kanga.kvack.org (Postfix) with ESMTP id DCDBD8E0006 for ; Wed, 8 Apr 2020 11:32:24 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 98E12513 for ; Wed, 8 Apr 2020 15:32:24 +0000 (UTC) X-FDA: 76685079408.28.spade07_896ade655362d X-HE-Tag: spade07_896ade655362d X-Filterd-Recvd-Size: 3325 Received: from mail-ed1-f68.google.com (mail-ed1-f68.google.com [209.85.208.68]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Wed, 8 Apr 2020 15:32:24 +0000 (UTC) Received: by mail-ed1-f68.google.com with SMTP id cf14so9040123edb.13 for ; Wed, 08 Apr 2020 08:32:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BuLVzhPxaop+SJ2whTddEzVfRFgewBRAzGdperrBJ00=; b=Ph6oKMMTV4T6nMg9XqwKDSJcFdiv7J0kHgIJzc6jjgp/w3CuRKVQ/NRwkXk5/842/5 DXUD1YfV8SzLZyXuZgrbOUC2hgbK0JNAb70V6BvVhQjqrk7q87yZRIONwQDGvYh/Ages lQGIg1d1VbDSXxufmWf03gR33HmPBcT4/ICZB+IbXNRaJxoqTFRcIa9Gh5d8LfnWm3or fbGLm2CIgSGWvqXW0g3pX99PjOh7p0E2vGq8SLNg5G/8eJN5pjPc6dDCdQRSS2F1Wp8h fiVOWSoRtvJhpLB0vpnxCwwRYDXILQRUeRqNjmveGvSCfRbUxArSHqoET4V57dGEIqRN 298Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BuLVzhPxaop+SJ2whTddEzVfRFgewBRAzGdperrBJ00=; b=cTuMwgFGVBdnCqe5nx6DHIfykfpm/aeoBPx0Fu9lIpbdrdsvVDbfW750xJTlWhBRGJ KRtykJvXcJw2yKJ7046Zh9giz+VpchFVhe/SqNQujF1/JdbLE80CTo+pWzd5UVmJJZm8 HLokQVuQsujxkMJk6l5c0Q3jpx0IGaOuVv/lVe3/s1APWYeXZ62Gv0aVM2KRYr6hA3FB Et/sbHi1VudI8noNwIBQkFH9DxzLgD+w7qdbyWgZWgSwLktPCN5rZAR9Rvu8l8JRsuV6 0lX6tptDuWFS8jn/dACj8nd6RIIGYPPLIjGCfWWru7lblzHTMst5VDqIrDormTFcW3lf hUfw== X-Gm-Message-State: AGi0PuZ+gXrmgyMZYeEmKkp/Q0A8fjqnnBdPnvvM2rxzKBH6Tr0Q+a8F Io2jd1wOwwYiqywPUT6YvEs/VIzKpVyNCeuK4mz5/g== X-Google-Smtp-Source: APiQypIZ3bXSE1Utxw9KKBoIpI8XJqlVybzENughSwUfL+PUdbCh8SUMBa1qNoXcCz0Zrsu1ILAUuAkVIYEimR5qB7Q= X-Received: by 2002:a50:aad3:: with SMTP id r19mr6828586edc.237.1586359943055; Wed, 08 Apr 2020 08:32:23 -0700 (PDT) MIME-Version: 1.0 References: <20200408150148.25290-1-willy@infradead.org> <20200408150148.25290-6-willy@infradead.org> In-Reply-To: <20200408150148.25290-6-willy@infradead.org> From: Pavel Tatashin Date: Wed, 8 Apr 2020 11:32:12 -0400 Message-ID: Subject: Re: [PATCH 5/5] mm: Check page poison before finding a head page To: Matthew Wilcox Cc: linux-mm , "Kirill A. Shutemov" Content-Type: text/plain; charset="UTF-8" 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 Wed, Apr 8, 2020 at 11:01 AM Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" > > If a page is poisoned, the page->compound_head will be set to -1. > Since it has bit zero set, we will think it is a tail page, and the head > page is at 0xff..fe. Checking said head page for being poisoned will > not have good results. Therefore we need to check for poison in each > of compound_head(), PageTail() and PageCompound() (and can remove the > checks which are now redundant from the PF_ macros). > > Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Pavel Tatashin