Re: + oom-sacrifice-child-with-highest-badness-score-for-parent-protect-dereferencing-of-tasks-comm.patch added to -mm tree

[KOSAKI Motohiro]

> 
> The patch titled
>      oom: protect dereferencing of task's comm
> has been added to the -mm tree.  Its filename is
>      oom-sacrifice-child-with-highest-badness-score-for-parent-protect-dereferencing-of-tasks-comm.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
> 
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
> 
> ------------------------------------------------------
> Subject: oom: protect dereferencing of task's comm
> From: David Rientjes <rientjes@xxxxxxxxxx>
> 
> Andrew notes that dereferencing task->comm is unsafe without holding
> task_lock(task).  That's true even when dealing with current, so all
> existing dereferences within the oom killer need to ensure they are
> holding task_lock() before doing so.
> 
> This avoids using get_task_comm() because we'd otherwise need to allocate
> a string of TASK_COMM_LEN on the stack (or add synchronization and use a
> global string) and we don't want to do that because page allocations, and
> thus the oom killer, can happen particularly deep in the stack.
> 
> Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Cc: Balbir Singh <balbir@xxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>



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