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    SubjectRe: [patch] zswap: fix zswap_frontswap_load() vs zsmalloc::map/unmap() might_sleep() splat
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    On Sat, 2020-12-19 at 11:46 +0100, Vitaly Wool wrote:
    > On Sat, 19 Dec 2020, 11:27 Mike Galbraith, <efault@gmx.de> wrote:
    >
    > > The kernel that generated that splat was NOT an RT kernel, it was plain
    > > master.today with a PREEMPT config.
    >
    >
    > I see, thanks. I don't think it makes things better for zsmalloc
    > though. From what I can see, the offending code is this:
    >
    > > /* From now on, migration cannot move the object */
    > > pin_tag(handle);
    >
    > Bit spinlock is taken in pin_tag(). I find the comment above somewhat
    > misleading, why is it necessary to take a spinlock to prevent
    > migration? I would guess an atomic flag should normally be enough.
    >
    > zswap is not broken here, it is zsmalloc that needs to be fixed.

    Cool, those damn bit spinlocks going away would be a case of happiness
    for RT as well :)

    -Mike

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