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Date:   Wed, 27 Sep 2023 10:14:10 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc:     maple-tree@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Jann Horn <jannh@google.com>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Suren Baghdasaryan <surenb@google.com>,
        Matthew Wilcox <willy@infradead.org>, stable@vger.kernel.org
Subject: Re: [PATCH 1/3] mmap: Fix vma_iterator in error path of vma_merge()
Message-Id: <20230927101410.920fd8a88d2453f5c530aff3@linux-foundation.org>
In-Reply-To: <20230927160746.1928098-2-Liam.Howlett@oracle.com>
References: <20230927160746.1928098-1-Liam.Howlett@oracle.com>
        <20230927160746.1928098-2-Liam.Howlett@oracle.com>
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On Wed, 27 Sep 2023 12:07:44 -0400 "Liam R. Howlett" <Liam.Howlett@oracle.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?