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Date:   Mon, 14 Aug 2023 09:55:03 +0200
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To:     Mateusz Guzik <mjguzik@gmail.com>, linux-kernel@vger.kernel.org
Cc:     torvalds@linux-foundation.org, brauner@kernel.org,
        ebiederm@xmission.com, akpm@linux-foundation.org,
        linux-mm@kvack.org, koct9i@gmail.com, oleg@redhat.com,
        dave@stgolabs.net
References: <20230813123333.1705833-1-mjguzik@gmail.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Subject: Re: [PATCH] kernel/fork: stop playing lockless games for exe_file
 replacement
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On 13.08.23 14:33, Mateusz Guzik wrote:
> xchg originated in 6e399cd144d8 ("prctl: avoid using mmap_sem for
> exe_file serialization"). While the commit message does not explain
> *why* the change, clearly the intent was to use mmap_sem less in this
> codepath. I found the original submission [1] which ultimately claims it
> cleans things up.

More details are apparently in v1 of that patch:

https://lore.kernel.org/lkml/1424979417.10344.14.camel@stgolabs.net/

Regarding your patch: adding more mmap_write_lock() where avoidable, I'm 
not so sure.

Your patch doesn't look (to me) like it is removing a lot of complexity.

-- 
Cheers,

David / dhildenb