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From: Zi Yan <ziy@nvidia.com>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	<saberlily.xia@hisilicon.com>, <linux-kernel@vger.kernel.org>,
	<linux-mm@kvack.org>, <kernel-team@fb.com>
Subject: Re: [PATCH v1 0/2] mm: cma: introduce a non-blocking version of cma_release()
Date: Thu, 22 Oct 2020 19:42:45 -0400	[thread overview]
Message-ID: <F8551A10-E254-44FC-B28E-9E7F8AC14B57@nvidia.com> (raw)
In-Reply-To: <20201022225308.2927890-1-guro@fb.com>

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On 22 Oct 2020, at 18:53, Roman Gushchin wrote:

> 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

Thanks for the patch. But during 1GB THP split, we only clear
the bitmaps without releasing the pages. Also in cma_release_nowait(),
the first page in the allocated CMA region is reused to store
struct cma_clear_bitmap_work, but the same method cannot be used
during THP split, since the first page is still in-use. We might
need to allocate some new memory for struct cma_clear_bitmap_work,
which might not be successful under memory pressure. Any suggestion
on where to store struct cma_clear_bitmap_work when I only want to
clear bitmap without releasing the pages?

Thanks.

—
Best Regards,
Yan Zi

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  parent reply	other threads:[~2020-10-22 23:43 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-22 22:53 [PATCH v1 0/2] mm: cma: introduce a non-blocking version of cma_release() Roman Gushchin
2020-10-22 22:53 ` [PATCH v1 1/2] mm: cma: introduce cma_release_nowait() Roman Gushchin
2020-10-24  7:59   ` Christoph Hellwig
2020-10-27 19:56     ` Roman Gushchin
2020-10-22 22:53 ` [PATCH v1 2/2] mm: hugetlb: don't drop hugetlb_lock around cma_release() call Roman Gushchin
2020-10-22 23:42 ` Zi Yan [this message]
2020-10-23  0:47   ` [PATCH v1 0/2] mm: cma: introduce a non-blocking version of cma_release() Roman Gushchin
2020-10-23  0:58     ` Zi Yan
2020-10-23 20:55       ` Roman Gushchin

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