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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