114 lines
5.0 KiB
Diff
114 lines
5.0 KiB
Diff
From patchwork Wed Mar 27 08:54:24 2019
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Date: Wed, 27 Mar 2019 08:54:24 +0000
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From: Mel Gorman <mgorman@techsingularity.net>
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To: Andrew Morton <akpm@linux-foundation.org>
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Cc: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>,
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Daniel Jordan <daniel.m.jordan@oracle.com>, Qian Cai <cai@lca.pw>,
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linux-mm@kvack.org, vbabka@suse.cz, linux-kernel@vger.kernel.org
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Subject: [PATCH] Correct zone boundary handling when resetting pageblock skip
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hints
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Mikhail Gavrilo reported the following bug being triggered in a Fedora
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kernel based on 5.1-rc1 but it is relevant to a vanilla kernel.
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kernel: page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
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kernel: ------------[ cut here ]------------
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kernel: kernel BUG at include/linux/mm.h:1021!
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kernel: invalid opcode: 0000 [#1] SMP NOPTI
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kernel: CPU: 6 PID: 116 Comm: kswapd0 Tainted: G C 5.1.0-0.rc1.git1.3.fc31.x86_64 #1
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kernel: Hardware name: System manufacturer System Product Name/ROG STRIX X470-I GAMING, BIOS 1201 12/07/2018
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kernel: RIP: 0010:__reset_isolation_pfn+0x244/0x2b0
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kernel: Code: fe 06 e8 0f 8e fc ff 44 0f b6 4c 24 04 48 85 c0 0f 85 dc fe ff ff e9 68 fe ff ff 48 c7 c6 58 b7 2e 8c 4c 89 ff e8 0c 75 00 00 <0f> 0b 48 c7 c6 58 b7 2e 8c e8 fe 74 00 00 0f 0b 48 89 fa 41 b8 01
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kernel: RSP: 0018:ffff9e2d03f0fde8 EFLAGS: 00010246
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kernel: RAX: 0000000000000034 RBX: 000000000081f380 RCX: ffff8cffbddd6c20
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kernel: RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8cffbddd6c20
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kernel: RBP: 0000000000000001 R08: 0000009898b94613 R09: 0000000000000000
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kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000100000
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kernel: R13: 0000000000100000 R14: 0000000000000001 R15: ffffca7de07ce000
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kernel: FS: 0000000000000000(0000) GS:ffff8cffbdc00000(0000) knlGS:0000000000000000
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kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
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kernel: CR2: 00007fc1670e9000 CR3: 00000007f5276000 CR4: 00000000003406e0
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kernel: Call Trace:
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kernel: __reset_isolation_suitable+0x62/0x120
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kernel: reset_isolation_suitable+0x3b/0x40
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kernel: kswapd+0x147/0x540
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kernel: ? finish_wait+0x90/0x90
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kernel: kthread+0x108/0x140
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kernel: ? balance_pgdat+0x560/0x560
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kernel: ? kthread_park+0x90/0x90
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kernel: ret_from_fork+0x27/0x50
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He bisected it down to commit e332f741a8dd ("mm, compaction: be selective
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about what pageblocks to clear skip hints"). The problem is that the patch
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in question was sloppy with respect to the handling of zone boundaries. In
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some instances, it was possible for PFNs outside of a zone to be examined
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and if those were not properly initialised or poisoned then it would
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trigger the VM_BUG_ON. This patch corrects the zone boundary issues when
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resetting pageblock skip hints and Mikhail reported that the bug did not
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trigger after 30 hours of testing.
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Fixes: e332f741a8dd ("mm, compaction: be selective about what pageblocks to clear skip hints")
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Reported-and-tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
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Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
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---
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mm/compaction.c | 27 +++++++++++++++++----------
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1 file changed, 17 insertions(+), 10 deletions(-)
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diff --git a/mm/compaction.c b/mm/compaction.c
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index f171a83707ce..b4930bf93c8a 100644
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--- a/mm/compaction.c
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+++ b/mm/compaction.c
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@@ -242,6 +242,7 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source,
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bool check_target)
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{
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struct page *page = pfn_to_online_page(pfn);
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+ struct page *block_page;
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struct page *end_page;
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unsigned long block_pfn;
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@@ -267,20 +268,26 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source,
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get_pageblock_migratetype(page) != MIGRATE_MOVABLE)
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return false;
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+ /* Ensure the start of the pageblock or zone is online and valid */
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+ block_pfn = pageblock_start_pfn(pfn);
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+ block_page = pfn_to_online_page(max(block_pfn, zone->zone_start_pfn));
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+ if (block_page) {
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+ page = block_page;
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+ pfn = block_pfn;
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+ }
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+
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+ /* Ensure the end of the pageblock or zone is online and valid */
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+ block_pfn += pageblock_nr_pages;
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+ block_pfn = min(block_pfn, zone_end_pfn(zone) - 1);
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+ end_page = pfn_to_online_page(block_pfn);
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+ if (!end_page)
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+ return false;
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+
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/*
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* Only clear the hint if a sample indicates there is either a
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* free page or an LRU page in the block. One or other condition
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* is necessary for the block to be a migration source/target.
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*/
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- block_pfn = pageblock_start_pfn(pfn);
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- pfn = max(block_pfn, zone->zone_start_pfn);
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- page = pfn_to_page(pfn);
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- if (zone != page_zone(page))
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- return false;
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- pfn = block_pfn + pageblock_nr_pages;
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- pfn = min(pfn, zone_end_pfn(zone));
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- end_page = pfn_to_page(pfn);
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-
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do {
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if (pfn_valid_within(pfn)) {
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if (check_source && PageLRU(page)) {
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@@ -309,7 +316,7 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source,
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static void __reset_isolation_suitable(struct zone *zone)
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{
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unsigned long migrate_pfn = zone->zone_start_pfn;
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- unsigned long free_pfn = zone_end_pfn(zone);
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+ unsigned long free_pfn = zone_end_pfn(zone) - 1;
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unsigned long reset_migrate = free_pfn;
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unsigned long reset_free = migrate_pfn;
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bool source_set = false;
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