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authorMichal Hocko <[email protected]>2019-11-05 21:16:40 -0800
committerLinus Torvalds <[email protected]>2019-11-06 08:47:50 -0800
commitabaed0112c1db08be15a784a2c5c8a8b3063cdd3 (patch)
tree844ee0bbda14fe055e6f45e66af79e492157c248
parentdf2ec7641bd03624a7e54cc926e8c3f75c7a84d8 (diff)
mm, vmstat: hide /proc/pagetypeinfo from normal users
/proc/pagetypeinfo is a debugging tool to examine internal page allocator state wrt to fragmentation. It is not very useful for any other use so normal users really do not need to read this file. Waiman Long has noticed that reading this file can have negative side effects because zone->lock is necessary for gathering data and that a) interferes with the page allocator and its users and b) can lead to hard lockups on large machines which have very long free_list. Reduce both issues by simply not exporting the file to regular users. Link: http://lkml.kernel.org/r/[email protected] Fixes: 467c996c1e19 ("Print out statistics in relation to fragmentation avoidance to /proc/pagetypeinfo") Signed-off-by: Michal Hocko <[email protected]> Reported-by: Waiman Long <[email protected]> Acked-by: Mel Gorman <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Acked-by: Waiman Long <[email protected]> Acked-by: Rafael Aquini <[email protected]> Acked-by: David Rientjes <[email protected]> Reviewed-by: Andrew Morton <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Konstantin Khlebnikov <[email protected]> Cc: Jann Horn <[email protected]> Cc: Song Liu <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--mm/vmstat.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6afc892a148a..4e885ecd44d1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1972,7 +1972,7 @@ void __init init_mm_internals(void)
#endif
#ifdef CONFIG_PROC_FS
proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
- proc_create_seq("pagetypeinfo", 0444, NULL, &pagetypeinfo_op);
+ proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);
proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
#endif