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Diffstat (limited to 'Documentation/filesystems/proc.txt')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index fcc1ac094282..219ffd41a911 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -515,6 +515,18 @@ be vanished or the reverse -- new added. This file is only present if the CONFIG_MMU kernel configuration option is enabled. +Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent +output can be achieved only in the single read call). +This typically manifests when doing partial reads of these files while the +memory map is being modified. Despite the races, we do provide the following +guarantees: + +1) The mapped addresses never go backwards, which implies no two + regions will ever overlap. +2) If there is something at a given vaddr during the entirety of the + life of the smaps/maps walk, there will be some output for it. + + The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG bits on both physical and virtual pages associated with a process, and the soft-dirty bit on pte (see Documentation/vm/soft-dirty.txt for details). |