linux-kernel - Re: [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and free

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Message-ID: <20200504164355.7551de82@gandalf.local.home>
Date:   Mon, 4 May 2020 16:43:55 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Joerg Roedel <jroedel@...e.de>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shile Zhang <shile.zhang@...ux.alibaba.com>,
        Andy Lutomirski <luto@...capital.net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Tzvetomir Stoyanov <tz.stoyanov@...il.com>
Subject: Re: [PATCH] percpu: Sync vmalloc mappings in pcpu_alloc() and
 free_percpu()

On Mon, 4 May 2020 22:25:40 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> I'm only following this with half an eye atm, but one solution is to
> pull the vmalloc fault out of the trace path entirely.
> 
> With the current code that is 'interesting', but with the pile of
> patches Thomas is sitting on that would be quite feasible.

As I assume that's not something that would be backported to the stable
kernels, I'm still going to add the workaround.

But getting rid of vmalloc_sync_mappings() altogether is still a good idea
IMO.

-- Steve