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[195.135.220.15]) by mx.google.com with ESMTPS id f20si2259004edy.431.2019.06.25.23.21.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Jun 2019 23:21:16 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 3619AAD47; Wed, 26 Jun 2019 06:21:15 +0000 (UTC) Date: Wed, 26 Jun 2019 08:21:13 +0200 From: Michal Hocko To: Alastair D'Silva Cc: alastair@d-silva.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Pavel Tatashin , Oscar Salvador , Mike Rapoport , Baoquan He , Wei Yang , Logan Gunthorpe , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 1/3] mm: Trigger bug on if a section is not found in __section_nr Message-ID: <20190626062113.GF17798@dhcp22.suse.cz> References: <20190626061124.16013-1-alastair@au1.ibm.com> <20190626061124.16013-2-alastair@au1.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190626061124.16013-2-alastair@au1.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 26-06-19 16:11:21, Alastair D'Silva wrote: > From: Alastair D'Silva > > If a memory section comes in where the physical address is greater than > that which is managed by the kernel, this function would not trigger the > bug and instead return a bogus section number. > > This patch tracks whether the section was actually found, and triggers the > bug if not. Why do we want/need that? In other words the changelog should contina WHY and WHAT. This one contains only the later one. > Signed-off-by: Alastair D'Silva > --- > drivers/base/memory.c | 18 +++++++++++++++--- > mm/sparse.c | 7 ++++++- > 2 files changed, 21 insertions(+), 4 deletions(-) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index f180427e48f4..9244c122abf1 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -585,13 +585,21 @@ int __weak arch_get_memory_phys_device(unsigned long start_pfn) > struct memory_block *find_memory_block_hinted(struct mem_section *section, > struct memory_block *hint) > { > - int block_id = base_memory_block_id(__section_nr(section)); > + int block_id, section_nr; > struct device *hintdev = hint ? &hint->dev : NULL; > struct device *dev; > > + section_nr = __section_nr(section); > + if (section_nr < 0) { > + if (hintdev) > + put_device(hintdev); > + return NULL; > + } > + > + block_id = base_memory_block_id(section_nr); > dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev); > - if (hint) > - put_device(&hint->dev); > + if (hintdev) > + put_device(hintdev); > if (!dev) > return NULL; > return to_memory_block(dev); > @@ -664,6 +672,10 @@ static int init_memory_block(struct memory_block **memory, > return -ENOMEM; > > scn_nr = __section_nr(section); > + > + if (scn_nr < 0) > + return scn_nr; > + > mem->start_section_nr = > base_memory_block_id(scn_nr) * sections_per_block; > mem->end_section_nr = mem->start_section_nr + sections_per_block - 1; > diff --git a/mm/sparse.c b/mm/sparse.c > index fd13166949b5..57a1a3d9c1cf 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -113,10 +113,15 @@ int __section_nr(struct mem_section* ms) > continue; > > if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT))) > - break; > + break; > } > > VM_BUG_ON(!root); > + if (root_nr == NR_SECTION_ROOTS) { > + VM_BUG_ON(true); > + > + return -EINVAL; > + } > > return (root_nr * SECTIONS_PER_ROOT) + (ms - root); > } > -- > 2.21.0 -- Michal Hocko SUSE Labs