The patch titled
Subject: memory-hotplug: don't replace lowmem pages with highmem
has been added to the -mm tree. Its filename is
memory-hotplug-dont-replace-lowmem-pages-with-highmem.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: memory-hotplug: don't replace lowmem pages with highmem
The changelog for 6a6dccba2 ("mm: cma: don't replace lowmem pages with
highmem") mentioned that lowmem pages can be replaced by highmem pages
during CMA migration. 6a6dccba2 fixed that issue.
Quote from that changelog:
: The filesystem layer expects pages in the block device's mapping to not
: be in highmem (the mapping's gfp mask is set in bdget()), but CMA can
: currently replace lowmem pages with highmem pages, leading to crashes in
: filesystem code such as the one below:
:
: Unable to handle kernel NULL pointer dereference at virtual address 00000400
: pgd = c0c98000
: [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000
: Internal error: Oops: 817 [#1] PREEMPT SMP ARM
: CPU: 0 Not tainted (3.5.0-rc5+ #80)
: PC is at __memzero+0x24/0x80
: ...
: Process fsstress (pid: 323, stack limit = 0xc0cbc2f0)
: Backtrace:
: [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98)
: [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc)
: r4:c15337f0
: [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98)
: [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac)
: r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0
: [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24)
: r6:beccdcf0 r5:00074000 r4:beccdbbc
: [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30)
Memory-hotplug has same problem as CMA has so the same fix can be applied
to memory-hotplug as well.
Fix it by reusing.
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff -puN mm/memory_hotplug.c~memory-hotplug-dont-replace-lowmem-pages-with-highmem mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~memory-hotplug-dont-replace-lowmem-pages-with-highmem
+++ a/mm/memory_hotplug.c
@@ -752,13 +752,6 @@ static unsigned long scan_lru_pages(unsi
return 0;
}
-static struct page *
-hotremove_migrate_alloc(struct page *page, unsigned long private, int **x)
-{
- /* This should be improooooved!! */
- return alloc_page(GFP_HIGHUSER_MOVABLE);
-}
-
#define NR_OFFLINE_AT_ONCE_PAGES (256)
static int
do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
@@ -809,8 +802,12 @@ do_migrate_range(unsigned long start_pfn
putback_lru_pages(&source);
goto out;
}
- /* this function returns # of failed pages */
- ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
+
+ /*
+ * alloc_migrate_target should be improooooved!!
+ * migrate_pages returns # of failed pages.
+ */
+ ret = migrate_pages(&source, alloc_migrate_target, 0,
true, MIGRATE_SYNC);
if (ret)
putback_lru_pages(&source);
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
memory-hotplug-reset-pgdat-kswapd-to-null-if-creating-kernel-thread-fails.patch
linux-next.patch
mm-remove-__gfp_no_kswapd.patch
mm-fix-nonuniform-page-status-when-writing-new-file-with-small-buffer.patch
mm-fix-nonuniform-page-status-when-writing-new-file-with-small-buffer-fix.patch
mm-fix-nonuniform-page-status-when-writing-new-file-with-small-buffer-fix-fix.patch
mm-compaction-update-comment-in-try_to_compact_pages.patch
mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures.patch
mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures-fix.patch
mm-compaction-capture-a-suitable-high-order-page-immediately-when-it-is-made-available.patch
mm-cma-discard-clean-pages-during-contiguous-allocation-instead-of-migration.patch
mm-move-all-mmu-notifier-invocations-to-be-done-outside-the-pt-lock-fix-fix.patch
mm-page_alloc-use-get_freepage_migratetype-instead-of-page_private.patch
mm-remain-migratetype-in-freed-page.patch
memory-hotplug-bug-fix-race-between-isolation-and-allocation.patch
memory-hotplug-fix-pages-missed-by-race-rather-than-failing.patch
memory-hotplug-fix-pages-missed-by-race-rather-than-failng-fix.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead-fix.patch
mm-memblock-reduce-overhead-in-binary-search.patch
mm-memblock-use-existing-interface-to-set-nid.patch
mm-memblock-cleanup-early_node_map-related-comments.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long-fix.patch
mm-compaction-check-lock-contention-first-before-taking-lock.patch
mm-page_alloc-refactor-out-__alloc_contig_migrate_alloc.patch
memory-hotplug-dont-replace-lowmem-pages-with-highmem.patch
--
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