linux-kernel - Re: [PATCH] prctl: Don't compile some of prctl functions when CRUI

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Message-ID: <20190417122349.GA15498@blackbody.suse.cz>
Date:   Wed, 17 Apr 2019 14:23:50 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Cyrill Gorcunov <gorcunov@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        kbuild-all@...org, LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Andrey Vagin <avagin@...nvz.org>,
        Andrew Morton <akpm@...uxfoundation.org>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        kbuild test robot <lkp@...el.com>
Subject: Re: [PATCH] prctl: Don't compile some of prctl functions when CRUI

Hi.

I see this discussion somewhat faded away since the previous year.

There was rework [1] that reduced (ab)use of mmap_sem in prctl
functions.

Actually, there still remains the down_write() in prctl_set_mm.
I considered at least replacing it with the mm_struct.arg_lock +
down_read() but then I learnt about this thread intending to remove that
part completely. I wouldn't oppose if CRIU is the sole (aware) user.

Ad the bot build issue, I could build the kernel both with
CONFIG_CHECKPOINT_RESTORE and without CONFIG_CHECKPOINT_RESTORE just
fine after applying the two proposed patches.

What is the current state? Perhaps, this change should be CCed to
linux-api@...r.kernel.org(?).

Thanks,
Michal

[1] https://lore.kernel.org/lkml/1523730291-109696-1-git-send-email-yang.shi@linux.alibaba.com/T/