Messages in this thread | | | From | Song Bao Hua <> | Subject | RE: [PATCH 8/8] mm/zswap: Use local lock to protect per-CPU data | Date | Tue, 19 May 2020 21:46:06 +0000 |
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> From: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
> zwap uses per-CPU compression. The per-CPU data pointer is acquired with > get_cpu_ptr() which implicitly disables preemption. It allocates memory inside the preempt disabled region which conflicts with the PREEMPT_RT semantics.
> Replace the implicit preemption control with an explicit local lock. > This allows RT kernels to substitute it with a real per CPU lock, which serializes the access but keeps the code section preemptible. On non RT kernels this maps to preempt_disable() as before, i.e. no functional change.
Hi Luis, In the below patch, in order to use the acomp APIs to leverage the power of hardware compressors. I have moved to mutex: https://marc.info/?l=linux-crypto-vger&m=158941285830302&w=2 https://marc.info/?l=linux-crypto-vger&m=158941287930311&w=2
so once we get some progress on that one, I guess we don't need a special patch for RT any more.
> [bigeasy: Use local_lock(), additional hunks, patch description]
> Cc: Seth Jennings <sjenning@redhat.com> > Cc: Dan Streetman <ddstreet@ieee.org> > Cc: Vitaly Wool <vitaly.wool@konsulko.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-mm@kvack.org > Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > mm/zswap.c | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-)
Thanks Barry
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