linux-kernel - Re: [PATCH v2 1/1] mm: do not increment pgfault stats when page fault handler retries

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Date:   Mon, 17 Apr 2023 17:26:04 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, willy@...radead.org, hannes@...xchg.org,
        mhocko@...e.com, josef@...icpanda.com, jack@...e.cz,
        ldufour@...ux.ibm.com, laurent.dufour@...ibm.com,
        michel@...pinasse.org, liam.howlett@...cle.com, jglisse@...gle.com,
        vbabka@...e.cz, minchan@...gle.com, dave@...olabs.net,
        punit.agrawal@...edance.com, lstoakes@...il.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v2 1/1] mm: do not increment pgfault stats when page
 fault handler retries

On Fri, Apr 14, 2023 at 05:08:18PM -0700, Suren Baghdasaryan wrote:
> @@ -5223,8 +5230,8 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
>  		if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
>  			mem_cgroup_oom_synchronize(false);
>  	}
> -
> -	mm_account_fault(regs, address, flags, ret);
> +out:
> +	mm_account_fault(mm, regs, address, flags, ret);

Ah, one more question.. can this cached mm race with a destroying mm (just
like the vma race we wanted to avoid)?  Still a question only applies to
COMPLETE case when mmap read lock can be released.  Thanks,

>  
>  	return ret;
>  }

-- 
Peter Xu