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[209.85.220.65]) by mx.google.com with SMTPS id j31sor18621230pgb.10.2019.03.25.18.59.38 for (Google Transport Security); Mon, 25 Mar 2019 18:59:39 -0700 (PDT) Received-SPF: pass (google.com: domain of zbestahu@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=S2991DI3; spf=pass (google.com: domain of zbestahu@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=zbestahu@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=tH7vupbA4qCrC0XFe2q1QYzpniBMj5XaFeIPW4wHzjo=; b=S2991DI3D741BudXvMXJRAwbOrj4Z83KFTqs5TWZPteSrwwReMpFVng4y24q+dSUes vjjfQtRsUyaP3VFPW5MMYWFVibXWk5s9h3lUWg9qii0zvkeoU2WIdfr6PMLX21SJ6FKr IJvQqc06yD169oUFkvxPvHRZ9xKBJUs7awpJFBtoYjLexj0ipv0XnMuxEasiqph7x96Y EcbSrjimxNsfrZ0kVHFusa/aSreBsWoxw4/0P0oVWulfAAXCZv7RKkk1nsvm/sUP6Hmf VV6Bo5chLxRmuo+NJNrEFhEkbFP1R4RswqSYNHCEur2sF/eiJtx4fAblWNxqEmm0CVij iMfw== X-Google-Smtp-Source: APXvYqwrBF88ljyPW3w05C/Hsm0RBcZX0sFAnuOFs7ZWUcueCH++wfcp0HI4+jQwCpsLdRyzpAMZoA== X-Received: by 2002:a63:4b0a:: with SMTP id y10mr26304521pga.66.1553565578594; Mon, 25 Mar 2019 18:59:38 -0700 (PDT) Received: from localhost ([218.189.10.173]) by smtp.gmail.com with ESMTPSA id u86sm39516753pfj.69.2019.03.25.18.59.35 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 25 Mar 2019 18:59:38 -0700 (PDT) Date: Tue, 26 Mar 2019 09:59:25 +0800 From: Yue Hu To: Andrew Morton Cc: iamjoonsoo.kim@lge.com, labbott@redhat.com, rppt@linux.vnet.ibm.com, rdunlap@infradead.org, linux-mm@kvack.org, huyue2@yulong.com, Anshuman Khandual Subject: Re: [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails Message-ID: <20190326095925.0000186d.zbestahu@gmail.com> In-Reply-To: <20190325151541.15350b039239ee9b331f3922@linux-foundation.org> References: <20190325081309.6004-1-zbestahu@gmail.com> <20190325151541.15350b039239ee9b331f3922@linux-foundation.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; i686-w64-mingw32) 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, 25 Mar 2019 15:15:41 -0700 Andrew Morton wrote: > On Mon, 25 Mar 2019 16:13:09 +0800 Yue Hu wrote: > > > From: Yue Hu > > > > A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation > > if CMA area can't be activated") fixes the crash issue when activation > > fails via setting cma->count as 0, same logic exists if bitmap > > allocation fails. > > > > --- a/mm/cma.c > > +++ b/mm/cma.c > > @@ -106,8 +106,10 @@ static int __init cma_activate_area(struct cma *cma) > > > > cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); > > > > - if (!cma->bitmap) > > + if (!cma->bitmap) { > > + cma->count = 0; > > return -ENOMEM; > > + } > > > > WARN_ON_ONCE(!pfn_valid(pfn)); > > zone = page_zone(pfn_to_page(pfn)); > > I'm unsure whether this is needed. > > kmalloc() within __init code is generally considered to be a "can't > fail". > > If this was the only issue then I guess I'd take the patch if only for > documentation/clarity purposes. But cma_areas[] is in bss and is > guaranteed to be all-zeroes, so I suspect this bug is a can't-happen. However, firstly cma->count will be assigned to size >> PAGE_SHIFT in cma_init_reserved_mem(). > And we could revert f022d8cb7ec7 if we could be bothered (I can't). > >