From patchwork Tue Dec 17 10:46:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11297239 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DDF2C6C1 for ; Tue, 17 Dec 2019 10:46:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9404621739 for ; Tue, 17 Dec 2019 10:46:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DHcSWb3s" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9404621739 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B5FF28E004F; Tue, 17 Dec 2019 05:46:48 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id B10A28E0040; Tue, 17 Dec 2019 05:46:48 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A08068E004F; Tue, 17 Dec 2019 05:46:48 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 868018E0040 for ; Tue, 17 Dec 2019 05:46:48 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 3AEAE180AD807 for ; Tue, 17 Dec 2019 10:46:48 +0000 (UTC) X-FDA: 76274305296.10.cows29_58597c0247b3c X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,david@redhat.com,:linux-kernel@vger.kernel.org::david@redhat.com:akpm@linux-foundation.org:dan.j.williams@intel.com:osalvador@suse.de:mhocko@kernel.org,RULES_HIT:30054:30056:30064:30070,0,RBL:205.139.110.120:@redhat.com:.lbl8.mailshell.net-62.18.0.100 66.10.201.10,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none X-HE-Tag: cows29_58597c0247b3c X-Filterd-Recvd-Size: 7492 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Tue, 17 Dec 2019 10:46:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576579606; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=EM2QWafeZ2TAQB5+5cMaXdVr5dTRW0WKU5lYjY+8TB0=; b=DHcSWb3sg2HBHvUAbEXSedTIMX+LsVPaXFYl1RuH0lLW6gMbtRyqR6pZ0TDPAPCVc6z/ji R1q54jRSbavRrMiKiAmddFnKH0nV/JU2dq832XgZ4Ob7EYZJcfpCPMV0WnQuduiQf686cI Nnxfw5cT6wNU0OsF9qJyhyFwW+IxAXM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-232-n-oX3rutPgWe9bnjGsH9Ew-1; Tue, 17 Dec 2019 05:46:43 -0500 X-MC-Unique: n-oX3rutPgWe9bnjGsH9Ew-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 077D763CDA; Tue, 17 Dec 2019 10:46:42 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.36.118.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id F3EEA60BE0; Tue, 17 Dec 2019 10:46:37 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Dan Williams , Oscar Salvador , Michal Hocko Subject: [PATCH v1] mm/memory_hotplug: Don't free usage map when removing a re-added early section Date: Tue, 17 Dec 2019 11:46:37 +0100 Message-Id: <20191217104637.5509-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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: When we remove an early section, we don't free the usage map, as the usage maps of other sections are placed into the same page. Once the section is removed, it is no longer an early section (especially, the memmap is freed). When we re-add that section, the usage map is reused, however, it is no longer an early section. When removing that section again, we try to kfree() a usage map that was allocated during early boot - bad. Let's check against PageReserved() to see if we are dealing with an usage map that was allocated during boot. We could also check against !(PageSlab(usage_page) || PageCompound(usage_page)), but PageReserved() is cleaner. Can be triggered using memtrace under ppc64/powernv: $ mount -t debugfs none /sys/kernel/debug/ $ echo 0x20000000 > /sys/kernel/debug/powerpc/memtrace/enable $ echo 0x20000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 12.093442] ------------[ cut here ]------------ [ 12.093469] kernel BUG at mm/slub.c:3969! [ 12.093656] Oops: Exception in kernel mode, sig: 5 [#1] [ 12.093961] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV [ 12.094320] Modules linked in: [ 12.094615] CPU: 0 PID: 154 Comm: sh Not tainted 5.5.0-rc2-next-20191216-00005-g0be1dba7b7c0 #61 [ 12.095066] NIP: c000000000396b38 LR: c000000000385848 CTR: c000000000143d30 [ 12.095427] REGS: c000000073077680 TRAP: 0700 Not tainted (5.5.0-rc2-next-20191216-00005-g0be1dba7b7c0) [ 12.095886] MSR: 900000000282b033 CR: 28004828 XER: 20000000 [ 12.096395] CFAR: c000000000396b9c IRQMASK: 0 [ 12.096395] GPR00: c000000000385848 c000000073077910 c00000000110f300 c00000007ffffc00 [ 12.096395] GPR04: 0000000000000000 ffffffffffffffff 0000000000000000 0000000000000000 [ 12.096395] GPR08: 0000000000000000 0000000000000001 0000000000000000 ffffffffffffffc8 [ 12.096395] GPR12: 0000000000004000 c0000000012d0000 0000000000001000 c000000000d33c78 [ 12.096395] GPR16: 0000000000000000 c0000000011bfeb0 ffffffffffffe000 c0000000000b6370 [ 12.096395] GPR20: ffffffffe0000000 c0000000011411c0 0000000000006000 c0000000000b6390 [ 12.096395] GPR24: 0000000010000000 0000000000000040 0000000000000000 0000000000000000 [ 12.096395] GPR28: c000000000385848 c00c0000001fffc0 0000000000004000 0000000000000000 [ 12.099882] NIP [c000000000396b38] kfree+0x338/0x3b0 [ 12.100135] LR [c000000000385848] section_deactivate+0x138/0x200 [ 12.100508] Call Trace: [ 12.100927] [c000000073077910] [c0000000010599a8] 0xc0000000010599a8 (unreliable) [ 12.101338] [c000000073077960] [c000000000385848] section_deactivate+0x138/0x200 [ 12.101696] [c000000073077a10] [c00000000039b9f4] __remove_pages+0x114/0x150 [ 12.102025] [c000000073077a60] [c00000000006793c] arch_remove_memory+0x3c/0x160 [ 12.102381] [c000000073077ae0] [c00000000039c154] try_remove_memory+0x114/0x1a0 [ 12.102715] [c000000073077b90] [c00000000039c020] __remove_memory+0x20/0x40 [ 12.103041] [c000000073077bb0] [c0000000000b6714] memtrace_enable_set+0x254/0x850 [ 12.103402] [c000000073077cb0] [c0000000004197e8] simple_attr_write+0x138/0x160 [ 12.103751] [c000000073077d10] [c000000000558c9c] full_proxy_write+0x8c/0x110 [ 12.104100] [c000000073077d60] [c0000000003d02a8] __vfs_write+0x38/0x70 [ 12.104409] [c000000073077d80] [c0000000003d3c5c] vfs_write+0x11c/0x2a0 [ 12.104711] [c000000073077dd0] [c0000000003d4054] ksys_write+0x84/0x140 [ 12.105011] [c000000073077e20] [c00000000000b594] system_call+0x5c/0x68 [ 12.105357] Instruction dump: [ 12.105606] e93d0000 75290001 41820090 8bfd0051 38a0ffff 7ca5f830 7bff0020 7ca507b4 [ 12.105993] e95d0000 39200000 754a0001 4182005c <0b090000> 893d0007 3d42000b 38800006 [ 12.106583] ---[ end trace 4b053cbd84e0db62 ]--- The first invocation will offline+remove memory blocks. The second invocation will first add+online them again, in order to offline+remove them again (usually we are lucky and the exact same memory blocks will get "reallocated"). Tested on powernv with boot memory: The usage map will not get freed. Tested on x86-64 with DIMMs: The usage map will get freed. Fixes: 326e1b8f83a4 ("mm/sparsemem: introduce a SECTION_IS_EARLY flag") Cc: Andrew Morton Cc: Dan Williams Cc: Oscar Salvador Cc: Michal Hocko Signed-off-by: David Hildenbrand Tested-by: Pingfan Liu --- mm/sparse.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/sparse.c b/mm/sparse.c index b20ab7cdac86..3822ecbd8a1f 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -777,7 +777,14 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) { unsigned long section_nr = pfn_to_section_nr(pfn); - if (!section_is_early) { + /* + * When removing an early section, the usage map is kept (as the + * usage maps of other sections fall into the same page). It + * will be re-used when re-adding the section - which is then no + * longer an early section. If the usage map is PageReserved, it + * was allocated during boot. + */ + if (!PageReserved(virt_to_page(ms->usage))) { kfree(ms->usage); ms->usage = NULL; }