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authorMikhail Zaslonko <zaslonko@linux.ibm.com>2019-02-01 14:20:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-02-01 15:46:23 -0800
commit24feb47c5fa5b825efb0151f28906dfdad027e61 (patch)
tree88fe4947cf578eab60b2dda1f6d8c257792294d3 /mm/memory_hotplug.c
parentefad4e475c312456edb3c789d0996d12ed744c13 (diff)
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: 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 Fix this by checking whether the pfn to check is within the zone. [mhocko@suse.com: separated this change from http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com] Link: http://lkml.kernel.org/r/20190128144506.15603-3-mhocko@kernel.org [mhocko@suse.com: separated this change from http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com] Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory_hotplug.c')
-rw-r--r--mm/memory_hotplug.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 91e6fef4cf9f..ecc5ee04e301 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1274,6 +1274,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
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;