Messages in this thread | | | Date | Mon, 7 Oct 2019 18:56:18 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] perf: rework memory accounting in perf_mmap() |
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On Mon, Oct 07, 2019 at 04:31:37PM +0000, Song Liu wrote: > Hi Peter, > > > On Sep 30, 2019, at 2:02 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > > > On Wed, Sep 04, 2019 at 02:46:18PM -0700, Song Liu wrote: > >> perf_mmap() always increases user->locked_vm. As a result, "extra" could > >> grow bigger than "user_extra", which doesn't make sense. Here is an > >> example case: > >> > >> Note: Assume "user_lock_limit" is very small. > >> | # of perf_mmap calls |vma->vm_mm->pinned_vm|user->locked_vm| > >> | 0 | 0 | 0 | > >> | 1 | user_extra | user_extra | > >> | 2 | 3 * user_extra | 2 * user_extra| > >> | 3 | 6 * user_extra | 3 * user_extra| > >> | 4 | 10 * user_extra | 4 * user_extra| > >> > >> Fix this by maintaining proper user_extra and extra. > > > > Aah, indeed. > > Thanks for the feedback! > > > > > Also, this code is unreadable (which is mostly my own fault I suppose) > > :/ > > How does this patch look to you? Is it ready to merge?
Yes, I queued it, I'll get it into tip soon. It got held up due to me working on some other patches, sorry about that.
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