Re: [RESEND][PATCH] Mark thread stack correctly in proc/<pid>/maps

From: Andrew Morton
Date: Wed Feb 22 2012 - 18:00:15 EST


On Tue, 21 Feb 2012 09:54:04 +0530
Siddhesh Poyarekar <siddhesh.poyarekar@xxxxxxxxx> wrote:

> Stack for a new thread is mapped by userspace code and passed via
> sys_clone. This memory is currently seen as anonymous in
> /proc/<pid>/maps, which makes it difficult to ascertain which mappings
> are being used for thread stacks. This patch uses the individual task
> stack pointers to determine which vmas are actually thread stacks.
>
> The display for maps, smaps and numa_maps is now different at the
> thread group (/proc/PID/maps) and thread (/proc/PID/task/TID/maps)
> levels. The idea is to give the mapping as the individual tasks see it
> in /proc/PID/task/TID/maps and then give an overview of the entire mm
> as it were, in /proc/PID/maps.
>
> At the thread group level, all vmas that are used as stacks are marked
> as such. At the thread level however, only the stack that the task in
> question uses is marked as such and all others (including the main
> stack) are marked as anonymous memory.

Please flesh this description out with specific examples of the
before-and-after contents of all the applicable procfs files. This way
we can clearly see the proposed interface changes, which is the thing
we care most about with such a patch.

The patch itself has been utterly and hopelessly mangled by gmail.
Please fix that up when resending (as a last resort: use a text/plain
attachment).

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