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SubjectRe: [PATCH 0/8] make hugetlb put_page safe for all calling contexts
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Hi:
On 2021/3/25 8:28, Mike Kravetz wrote:
> This effort is the result a recent bug report [1]. In subsequent
> discussions [2], it was deemed necessary to properly fix the hugetlb

Many thanks for the effort. I have read the discussions and it is pretty long.
Maybe it would be helpful if you give a brief summary here?

> put_page path (free_huge_page). This RFC provides a possible way to

trival: Not RFC here.

> address the issue. Comments are welcome/encouraged as several attempts
> at this have been made in the past.
> > This series is based on v5.12-rc3-mmotm-2021-03-17-22-24. At a high
> level, the series provides:
> - Patches 1 & 2 from Roman Gushchin provide cma_release_nowait()

trival: missing description of the Patches 3 ?

> - Patches 4, 5 & 6 are aimed at reducing lock hold times. To be clear
> the goal is to eliminate single lock hold times of a long duration.
> Overall lock hold time is not addressed.
> - Patch 7 makes hugetlb_lock and subpool lock IRQ safe. It also reverts
> the code which defers calls to a workqueue if !in_task.
> - Patch 8 adds some lockdep_assert_held() calls
>
> [1] https://lore.kernel.org/linux-mm/000000000000f1c03b05bc43aadc@google.com/
> [2] http://lkml.kernel.org/r/20210311021321.127500-1-mike.kravetz@oracle.com
>
> RFC -> v1
> - Add Roman's cma_release_nowait() patches. This eliminated the need
> to do a workqueue handoff in hugetlb code.
> - Use Michal's suggestion to batch pages for freeing. This eliminated
> the need to recalculate loop control variables when dropping the lock.
> - Added lockdep_assert_held() calls
> - Rebased to v5.12-rc3-mmotm-2021-03-17-22-24
>
> Mike Kravetz (6):
> hugetlb: add per-hstate mutex to synchronize user adjustments
> hugetlb: create remove_hugetlb_page() to separate functionality
> hugetlb: call update_and_free_page without hugetlb_lock
> hugetlb: change free_pool_huge_page to remove_pool_huge_page
> hugetlb: make free_huge_page irq safe
> hugetlb: add lockdep_assert_held() calls for hugetlb_lock
>
> 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 +
> include/linux/hugetlb.h | 1 +
> mm/cma.c | 93 +++++++++++
> mm/cma.h | 5 +
> mm/hugetlb.c | 354 +++++++++++++++++++++-------------------
> mm/hugetlb_cgroup.c | 8 +-
> 6 files changed, 294 insertions(+), 169 deletions(-)
>

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