The patch titled
Subject: mm, memory_hotplug: test_pages_in_a_zone do not pass the end of zone
has been added to the -mm tree. Its filename is
mm-memory_hotplug-test_pages_in_a_zone-do-not-pass-the-end-of-zone.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-test_pages_in_a_zone-do-not-pass-the-end-of-zone.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-test_pages_in_a_zone-do-not-pass-the-end-of-zone.patch
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------------------------------------------------------
From: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>
Subject: mm, memory_hotplug: test_pages_in_a_zone do not pass the end of zone
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 pages access from
test_pages_in_a_zone() function triggered by memory_hotplug sysfs
handlers.
Here are the the panic examples:
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:
([<0000000000385b26>] test_pages_in_a_zone+0xde/0x160)
[<00000000008f15c4>] show_valid_zones+0x5c/0x190
[<00000000008cf9c4>] dev_attr_show+0x34/0x70
[<0000000000463ad0>] sysfs_kf_seq_show+0xc8/0x148
[<00000000003e4194>] seq_read+0x204/0x480
[<00000000003b53ea>] __vfs_read+0x32/0x178
[<00000000003b55b2>] vfs_read+0x82/0x138
[<00000000003b5be2>] ksys_read+0x5a/0xb0
[<0000000000b86ba0>] system_call+0xdc/0x2d8
Last Breaking-Event-Address:
[<0000000000385b26>] test_pages_in_a_zone+0xde/0x160
Kernel panic - not syncing: Fatal exception: panic_on_oops
Fix this by checking whether the pfn to check is within the zone.
[mhocko@xxxxxxxx: separated this change from http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@xxxxxxxxxxxxx]
Link: http://lkml.kernel.org/r/20190128144506.15603-3-mhocko@xxxxxxxxxx
Signed-off-by: Mikhail Zaslonko <zaslonko@xxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Mikhail Gavrilov <mikhail.v.gavrilov@xxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-test_pages_in_a_zone-do-not-pass-the-end-of-zone
+++ a/mm/memory_hotplug.c
@@ -1287,6 +1287,9 @@ int test_pages_in_a_zone(unsigned long s
i++;
if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
continue;
+ /* Check if we got outside of the zone */
+ if (zone && !zone_spans_pfn(zone, pfn + i))
+ return 0;
page = pfn_to_page(pfn + i);
if (zone && page_zone(page) != zone)
return 0;
_
Patches currently in -mm which might be from zaslonko@xxxxxxxxxxxxx are
mm-memory_hotplug-test_pages_in_a_zone-do-not-pass-the-end-of-zone.patch
