linux-kernel - Re: [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM

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Date:   Mon, 22 Aug 2022 15:21:19 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     mhocko@...e.com, rientjes@...gle.com, willy@...radead.org,
        hannes@...xchg.org, guro@...com, minchan@...nel.org,
        kirill@...temov.name, aarcange@...hat.com, brauner@...nel.org,
        hch@...radead.org, oleg@...hat.com, david@...hat.com,
        jannh@...gle.com, shakeelb@...gle.com, peterx@...hat.com,
        jhubbard@...dia.com, shuah@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org, kernel-team@...roid.com,
        Yu Zhao <yuzhao@...gle.com>
Subject: Re: [PATCH RESEND v2 2/2] mm: delete unused MMF_OOM_VICTIM flag

On Tue, 31 May 2022 15:31:00 -0700 Suren Baghdasaryan <surenb@...gle.com> wrote:

> With the last usage of MMF_OOM_VICTIM in exit_mmap gone, this flag is
> now unused and can be removed.
> 
> ...
>
> --- a/include/linux/oom.h
> +++ b/include/linux/oom.h
> @@ -77,15 +77,6 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk)
>  	return tsk->signal->oom_mm;
>  }
>  
> -/*
> - * Use this helper if tsk->mm != mm and the victim mm needs a special
> - * handling. This is guaranteed to stay true after once set.
> - */
> -static inline bool mm_is_oom_victim(struct mm_struct *mm)
> -{
> -	return test_bit(MMF_OOM_VICTIM, &mm->flags);
> -}
> -

The patch "mm: multi-gen LRU: support page table walks" from the MGLRU
series
(https://lkml.kernel.org/r/20220815071332.627393-9-yuzhao@google.com)
adds two calls to mm_is_oom_victim(), so my build broke.

I assume the fix is simply

--- a/mm/vmscan.c~mm-delete-unused-mmf_oom_victim-flag-fix
+++ a/mm/vmscan.c
@@ -3429,9 +3429,6 @@ static bool should_skip_mm(struct mm_str
 	if (size < MIN_LRU_BATCH)
 		return true;
 
-	if (mm_is_oom_victim(mm))
-		return true;
-
 	return !mmget_not_zero(mm);
 }
 
@@ -4127,9 +4124,6 @@ restart:
 
 		walk_pmd_range(&val, addr, next, args);
 
-		if (mm_is_oom_victim(args->mm))
-			return 1;
-
 		/* a racy check to curtail the waiting time */
 		if (wq_has_sleeper(&walk->lruvec->mm_state.wait))
 			return 1;
_

Please confirm?