Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1561438

Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath

Show all headers | View raw

On Wed 18-01-17 10:48:55, Vlastimil Babka wrote:
> On 01/18/2017 10:40 AM, Michal Hocko wrote:
> > On Tue 17-01-17 23:16:09, Vlastimil Babka wrote:
> > > This is a preparation for the following patch to make review simpler. While
> > > the primary motivation is a bug fix, this could also save some cycles in the
> > > fast path.
> > 
> > I cannot say I would be happy about this patch :/ The code is still very
> > confusing and subtle. I really think we should get rid of
> > synchronization with the concurrent cpuset/mempolicy updates instead.
> > Have you considered that instead?
> 
> Not so thoroughly yet, but I already suspect it would be intrusive for
> stable. We could make copies of nodemask and mems_allowed and protect just
> the copying with seqcount, but that would mean overhead and stack space.
> Also we might try revert 682a3385e773 ("mm, page_alloc: inline the fast path
> of the zonelist iterator") ...

If reverting that patch makes the problem go away and it is applicable
for the stable I would rather go that way for stable and take a deep
breath and rethink the whole cpuset and nodemask manipulation in the
allocation path for a better long term solution.

-- 
Michal Hocko
SUSE Labs

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[RFC 0/4] fix premature OOM due to cpuset races Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 01:10 +0100
  [RFC 4/4] mm, page_alloc: fix premature OOM when racing with cpuset mems update Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 01:10 +0100
    Re: [RFC 4/4] mm, page_alloc: fix premature OOM when racing with cpuset mems update "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-01-18 08:20 +0100
      Re: [RFC 4/4] mm, page_alloc: fix premature OOM when racing with  cpuset mems update Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 10:40 +0100
    Re: [RFC 4/4] mm, page_alloc: fix premature OOM when racing with  cpuset mems update Mel Gorman <mgorman@techsingularity.net> - 2017-01-18 11:20 +0100
  [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 01:20 +0100
    Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-01-18 08:40 +0100
      Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to  slowpath Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 10:30 +0100
    Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to  slowpath Mel Gorman <mgorman@techsingularity.net> - 2017-01-18 11:10 +0100
    Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to  slowpath Michal Hocko <mhocko@kernel.org> - 2017-01-18 11:10 +0100
      Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to  slowpath Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 11:10 +0100
        Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to  slowpath Michal Hocko <mhocko@kernel.org> - 2017-01-18 11:20 +0100
  [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update or removal Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 01:20 +0100
    Re: [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update  or removal Michal Hocko <mhocko@kernel.org> - 2017-01-18 10:40 +0100
    Re: [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update  or removal Mel Gorman <mgorman@techsingularity.net> - 2017-01-18 10:50 +0100
  Re: [RFC 0/4] fix premature OOM due to cpuset races Michal Hocko <mhocko@kernel.org> - 2017-01-18 10:40 +0100
  [RFC 5/4] mm, page_alloc: fix premature OOM due to vma mempolicy  update Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 17:30 +0100
    Re: [RFC 5/4] mm, page_alloc: fix premature OOM due to vma mempolicy  update Vlastimil Babka <vbabka@suse.cz> - 2017-01-18 17:30 +0100

csiph-web