Re: [PATCH v2 4/6] mm: hugetlb: add return -EAGAIN for dissolve_free_huge_page
From: Michal Hocko <mhocko@suse.com>
Date: 2021-01-06 17:09:00
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On Wed 06-01-21 16:47:37, Muchun Song wrote:
When dissolve_free_huge_page() races with __free_huge_page(), we can do a retry. Because the race window is small.
Is this a bug fix or mere optimization. I have hard time to tell from the description.
quoted hunk ↗ jump to hunk
Signed-off-by: Muchun Song <redacted> --- mm/hugetlb.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-)diff --git a/mm/hugetlb.c b/mm/hugetlb.c
[...]
quoted hunk ↗ jump to hunk
@@ -1825,6 +1828,14 @@ int dissolve_free_huge_page(struct page *page) } out: spin_unlock(&hugetlb_lock); + + /* + * If the freeing of the HugeTLB page is put on a work queue, we should + * flush the work before retrying. + */ + if (unlikely(rc == -EAGAIN)) + flush_work(&free_hpage_work);
Is it safe to wait for the work to finish from this context? -- Michal Hocko SUSE Labs