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authorSai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>2019-09-25 16:47:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-25 17:51:40 -0700
commit8495f7e6732ed248b648d36439795b42ec650b9e (patch)
tree6bf586c2f23b31c2f908ed3b19536099e066b4b0 /include/linux
parentaadc4e01dbaaccd38abde03bc84d0332a6bd9eab (diff)
fork: improve error message for corrupted page tables
When a user process exits, the kernel cleans up the mm_struct of the user process and during cleanup, check_mm() checks the page tables of the user process for corruption (E.g: unexpected page flags set/cleared). For corrupted page tables, the error message printed by check_mm() isn't very clear as it prints the loop index instead of page table type (E.g: Resident file mapping pages vs Resident shared memory pages). The loop index in check_mm() is used to index rss_stat[] which represents individual memory type stats. Hence, instead of printing index, print memory type, thereby improving error message. Without patch: -------------- [ 204.836425] mm/pgtable-generic.c:29: bad p4d 0000000089eb4e92(800000025f941467) [ 204.836544] BUG: Bad rss-counter state mm:00000000f75895ea idx:0 val:2 [ 204.836615] BUG: Bad rss-counter state mm:00000000f75895ea idx:1 val:5 [ 204.836685] BUG: non-zero pgtables_bytes on freeing mm: 20480 With patch: ----------- [ 69.815453] mm/pgtable-generic.c:29: bad p4d 0000000084653642(800000025ca37467) [ 69.815872] BUG: Bad rss-counter state mm:00000000014a6c03 type:MM_FILEPAGES val:2 [ 69.815962] BUG: Bad rss-counter state mm:00000000014a6c03 type:MM_ANONPAGES val:5 [ 69.816050] BUG: non-zero pgtables_bytes on freeing mm: 20480 Also, change print function (from printk(KERN_ALERT, ..) to pr_alert()) so that it matches the other print statement. Link: http://lkml.kernel.org/r/da75b5153f617f4c5739c08ee6ebeb3d19db0fbc.1565123758.git.sai.praneeth.prakhya@intel.com Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Suggested-by: Dave Hansen <dave.hansen@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Dave Hansen <dave.hansen@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/mm_types_task.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/mm_types_task.h b/include/linux/mm_types_task.h
index d7016dcb245e..c1bc6731125c 100644
--- a/include/linux/mm_types_task.h
+++ b/include/linux/mm_types_task.h
@@ -36,6 +36,10 @@ struct vmacache {
struct vm_area_struct *vmas[VMACACHE_SIZE];
};
+/*
+ * When updating this, please also update struct resident_page_types[] in
+ * kernel/fork.c
+ */
enum {
MM_FILEPAGES, /* Resident file mapping pages */
MM_ANONPAGES, /* Resident anonymous pages */

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