linux-kernel - Re: [PATCH 1/3] mmap: Fix vma_iterator in error path of vma

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Message-Id: <20230927101410.920fd8a88d2453f5c530aff3@linux-foundation.org>
Date:   Wed, 27 Sep 2023 10:14:10 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Jann Horn <jannh@...gle.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Matthew Wilcox <willy@...radead.org>, stable@...r.kernel.org
Subject: Re: [PATCH 1/3] mmap: Fix vma_iterator in error path of vma_merge()

On Wed, 27 Sep 2023 12:07:44 -0400 "Liam R. Howlett" <Liam.Howlett@...cle.com> wrote:

> When merging of the previous VMA fails after the vma iterator has been
> moved to the previous entry, the vma iterator must be advanced to ensure
> the caller takes the correct action on the next vma iterator event.  Fix
> this by adding a vma_next() call to the error path.
> 
> Users may experience higher CPU usage, most likely in very low memory
> situations.

Looking through this thread:

> Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/

I'm seeing no indication that the effect is CPU consumption?  Jann is
excpecting bogus oom-killing?