Re: [PATCH v3 2/2] Documentation/filesystems/proc.txt: Add more description for maps/smaps

[Robert Hu <robert.hu@vmm.sh.intel.com>]

On Fri, 2016-09-23 at 09:06 -0700, Dave Hansen wrote:
> On 09/23/2016 06:12 AM, Robert Ho wrote:
> > +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.
> 
> Could we spuce this description up a bit?  Perhaps:
> 
> Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy.
> 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.
Sure. Thanks Dave for helping make it more concise and correct.



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