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[198.145.29.99]) by mx.google.com with ESMTPS id l95si20430014plb.365.2019.05.07.09.58.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 May 2019 09:58:01 -0700 (PDT) Received-SPF: pass (google.com: domain of sashal@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=bxzD848w; spf=pass (google.com: domain of sashal@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=sashal@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3AC28205C9; Tue, 7 May 2019 16:58:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557248281; bh=k0O6Zge2oYkJ/odPfWebdw/rC3Kt7k/XfPt85IyTuts=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bxzD848w88aw9JlTkU1D/e4kM4RgnsvgrixKzJEpThPfyJCTdJ4fmEddixgchjZIv vJWsZ5ifLdYumEveNY7R7AK1YEVaPkjXKhwiP30AfFTWrrahCBv8ka1FCwffkp6/ef cM0tDcxxsP38LUAmlv8pQmg5aeclviHWWtHqKMH0= Date: Tue, 7 May 2019 12:58:00 -0400 From: Sasha Levin To: Alexander Duyck Cc: LKML , stable@vger.kernel.org, Mikhail Zaslonko , Gerald Schaefer , Michal Hocko , Michal Hocko , Mikhail Gavrilov , Dave Hansen , Alexander Duyck , Pasha Tatashin , Martin Schwidefsky , Heiko Carstens , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm Subject: Re: [PATCH AUTOSEL 4.14 62/95] mm, memory_hotplug: initialize struct pages for the full memory section Message-ID: <20190507165800.GE1747@sasha-vm> References: <20190507053826.31622-1-sashal@kernel.org> <20190507053826.31622-62-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: 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 Tue, May 07, 2019 at 09:31:10AM -0700, Alexander Duyck wrote: >On Mon, May 6, 2019 at 10:40 PM Sasha Levin wrote: >> >> From: Mikhail Zaslonko >> >> [ Upstream commit 2830bf6f05fb3e05bc4743274b806c821807a684 ] >> >> If memory end is not aligned with the sparse memory section boundary, >> the mapping of such a section is only partly initialized. This may lead >> to VM_BUG_ON due to uninitialized struct page access from >> is_mem_section_removable() or test_pages_in_a_zone() function triggered >> by memory_hotplug sysfs handlers: >> >> Here are the the panic examples: >> CONFIG_DEBUG_VM=y >> CONFIG_DEBUG_VM_PGFLAGS=y >> >> kernel parameter mem=2050M >> -------------------------- >> page:000003d082008000 is uninitialized and poisoned >> page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) >> Call Trace: >> ( test_pages_in_a_zone+0xde/0x160) >> show_valid_zones+0x5c/0x190 >> dev_attr_show+0x34/0x70 >> sysfs_kf_seq_show+0xc8/0x148 >> seq_read+0x204/0x480 >> __vfs_read+0x32/0x178 >> vfs_read+0x82/0x138 >> ksys_read+0x5a/0xb0 >> system_call+0xdc/0x2d8 >> Last Breaking-Event-Address: >> test_pages_in_a_zone+0xde/0x160 >> Kernel panic - not syncing: Fatal exception: panic_on_oops >> >> kernel parameter mem=3075M >> -------------------------- >> page:000003d08300c000 is uninitialized and poisoned >> page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) >> Call Trace: >> ( is_mem_section_removable+0xb4/0x190) >> show_mem_removable+0x9a/0xd8 >> dev_attr_show+0x34/0x70 >> sysfs_kf_seq_show+0xc8/0x148 >> seq_read+0x204/0x480 >> __vfs_read+0x32/0x178 >> vfs_read+0x82/0x138 >> ksys_read+0x5a/0xb0 >> system_call+0xdc/0x2d8 >> Last Breaking-Event-Address: >> is_mem_section_removable+0xb4/0x190 >> Kernel panic - not syncing: Fatal exception: panic_on_oops >> >> Fix the problem by initializing the last memory section of each zone in >> memmap_init_zone() till the very end, even if it goes beyond the zone end. >> >> Michal said: >> >> : This has alwways been problem AFAIU. It just went unnoticed because we >> : have zeroed memmaps during allocation before f7f99100d8d9 ("mm: stop >> : zeroing memory during allocation in vmemmap") and so the above test >> : would simply skip these ranges as belonging to zone 0 or provided a >> : garbage. >> : >> : So I guess we do care for post f7f99100d8d9 kernels mostly and >> : therefore Fixes: f7f99100d8d9 ("mm: stop zeroing memory during >> : allocation in vmemmap") >> >> Link: http://lkml.kernel.org/r/20181212172712.34019-2-zaslonko@linux.ibm.com >> Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") >> Signed-off-by: Mikhail Zaslonko >> Reviewed-by: Gerald Schaefer >> Suggested-by: Michal Hocko >> Acked-by: Michal Hocko >> Reported-by: Mikhail Gavrilov >> Tested-by: Mikhail Gavrilov >> Cc: Dave Hansen >> Cc: Alexander Duyck >> Cc: Pasha Tatashin >> Cc: Martin Schwidefsky >> Cc: Heiko Carstens >> Cc: >> Signed-off-by: Andrew Morton >> Signed-off-by: Linus Torvalds >> Signed-off-by: Sasha Levin >> --- >> mm/page_alloc.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) > >Wasn't this patch reverted in Linus's tree for causing a regression on >some platforms? If so I'm not sure we should pull this in as a >candidate for stable should we, or am I missing something? I saw a follow-up patch that should be queued too, but I didn't see that this one got reverted. -- Thanks, Sasha