linux-kernel - [PATCH v1 0/2] mm: cma: introduce a non-blocking version of cma

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Date:   Thu, 22 Oct 2020 15:53:06 -0700
From:   Roman Gushchin <guro@...com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     Zi Yan <ziy@...dia.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        <saberlily.xia@...ilicon.com>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <kernel-team@...com>,
        Roman Gushchin <guro@...com>
Subject: [PATCH v1 0/2] mm: cma: introduce a non-blocking version of cma_release()

This small patchset introduces a non-blocking version of cma_release()
and simplifies the code in hugetlbfs, where previously we had to
temporarily drop hugetlb_lock around the cma_release() call.

It should help Zi Yan on his work on 1 GB THPs: splitting a gigantic
THP under a memory pressure requires a cma_release() call. If it's
a blocking function, it complicates the already complicated code.
Because there are at least two use cases like this (hugetlbfs is
another example), I believe it's just better to make cma_release()
non-blocking.

v1:
  - introduce cma_release_nowait() instead of making cma_release()
    non-blocking, for performance reasons

rfc:
  https://lkml.org/lkml/2020/10/16/1050

Roman Gushchin (2):
  mm: cma: introduce cma_release_nowait()
  mm: hugetlb: don't drop hugetlb_lock around cma_release() call

 include/linux/cma.h |  2 +
 mm/cma.c            | 93 +++++++++++++++++++++++++++++++++++++++++++++
 mm/cma.h            |  5 +++
 mm/hugetlb.c        | 11 ++----
 4 files changed, 103 insertions(+), 8 deletions(-)

-- 
2.26.2