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From:   Suren Baghdasaryan <surenb@google.com>
Date:   Tue, 18 Apr 2023 09:45:52 -0700
Message-ID: <CAJuCfpGuF_kKXMSx2bHNC7FprOfqbCp+cfdsoct9sN=1+wqtAQ@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] mm: do not increment pgfault stats when page fault
 handler retries
To:     Peter Xu <peterx@redhat.com>
Cc:     Matthew Wilcox <willy@infradead.org>, akpm@linux-foundation.org,
        hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com,
        jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com,
        michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com,
        vbabka@suse.cz, minchan@google.com, dave@stgolabs.net,
        punit.agrawal@bytedance.com, lstoakes@gmail.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        kernel-team@android.com
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On Tue, Apr 18, 2023 at 8:48=E2=80=AFAM Peter Xu <peterx@redhat.com> wrote:
>
> On Tue, Apr 18, 2023 at 04:32:27PM +0100, Matthew Wilcox wrote:
> > ... when we called clone()?  A thread by definition has a reference to
> > its own mm.
>
> Ah yes.. thanks!

re: I also had a quick look on do_exit() but I also didn't see where
do we e.g. wait for all the threads to stop before recycles a mm.

We recycle mm after all refcounts are dropped in the exit path:
  do_exit
    exit_mm
      mmput(if !mm->mm_users)
        mmdrop(if !mm->mm_count)
          free_mm

>
> --
> Peter Xu
>