linux-kernel - [PATCH rfc 0/2] mm: cma: make cma

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Message-ID: <20201016225254.3853109-1-guro@fb.com>
Date:   Fri, 16 Oct 2020 15:52:52 -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>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <kernel-team@...com>, Roman Gushchin <guro@...com>
Subject: [PATCH rfc 0/2] mm: cma: make cma_release() non-blocking

This small patchset makes cma_release() non-blocking 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.

It also makes it more consistent with other memory releasing functions
in the kernel: most of them are non-blocking.

Roman Gushchin (2):
  mm: cma: make cma_release() non-blocking
  mm: hugetlb: don't drop hugetlb_lock around cma_release() call

 mm/cma.c     | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 mm/hugetlb.c |  6 ------
 2 files changed, 49 insertions(+), 8 deletions(-)

-- 
2.26.2