[PATCH v3 2/2] Documentation/filesystems/proc.txt: Add more description for maps/smaps
From: Robert Ho <hidden>
Date: 2016-09-23 13:13:44
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documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
Add some more description on the limitations for smaps/maps readings, as well as some guaruntees we can make. Signed-off-by: Robert Ho <redacted> --- Documentation/filesystems/proc.txt | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 68080ad..90eabc7 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt@@ -515,6 +515,14 @@ be vanished or the reverse -- new added. This file is only present if the CONFIG_MMU kernel configuration option is enabled. +Note: for both /proc/PID/maps and /proc/PID/smaps readings, it's +possible in race conditions, that the mappings printed may not be that +up-to-date, because during each read walking, the task's mappings may have +changed, this typically happens in multithread cases. But anyway in each single +read these can be guarunteed: 1) the mapped addresses doesn't go backward; 2) no +overlaps 3) 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).
--
1.8.3.1
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