On Thu 05-11-15 18:50:29, Andrew Morton wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
> Subject: memcg: fix thresholds for 32b architectures.
>
> 424cdc141380 ("memcg: convert threshold to bytes") has fixed a regression
> introduced by 3e32cb2e0a12 ("mm: memcontrol: lockless page counters")
> where thresholds were silently converted to use page units rather than
> bytes when interpreting the user input.
>
> The fix is not complete, though, as properly pointed out by Ben Hutchings
> during stable backport review. The page count is converted to bytes but
> unsigned long is used to hold the value which would be obviously not
> sufficient for 32b systems with more than 4G thresholds. The same applies
> to usage as taken from mem_cgroup_usage which might overflow.
>
> Let's remove this bytes vs. pages internal tracking differences and
> handle thresholds in page units internally. Chage mem_cgroup_usage() to
> return the value in page units and revert 424cdc141380 because this should
> be sufficient for the consistent handling. mem_cgroup_read_u64 as the
> only users of mem_cgroup_usage outside of the threshold handling code is
> converted to give the proper in bytes result. It is doing that already
> for page_counter output so this is more consistent as well.
>
> The value presented to the userspace is still in bytes units.
>
> Fixes: 424cdc141380 ("memcg: convert threshold to bytes")
> Fixes: 3e32cb2e0a12 ("mm: memcontrol: lockless page counters")
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> Reviewed-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
-----
> From: Michal Hocko <mhocko@xxxxxxxxxx>
> Subject: memcg-fix-thresholds-for-32b-architectures-fix
>
> Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Subject: memcg-fix-thresholds-for-32b-architectures-fix-fix
>
> don't attempt to inline mem_cgroup_usage()
>
> The compiler ignores the inline anwyay. And __always_inlining it adds 600
> bytes of goop to the .o file.
>
> Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
This doesn't belong to the changelog. The patch is OK otherwise.
--
Michal Hocko
SUSE Labs
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