Hugh Dickins wrote: > Occasionally we hit the BUG_ON(pmd_trans_huge(*pmd)) at the end of > __split_huge_page_pmd(): seen when doing madvise(,,MADV_DONTNEED). > > It's invalid: we don't always have down_write of mmap_sem there: > a racing do_huge_pmd_wp_page() might have copied-on-write to another > huge page before our split_huge_page() got the anon_vma lock. > > Forget the BUG_ON, just go back and try again if this happens. > > Signed-off-by: Hugh Dickins <[email protected]> > Cc: [email protected]
Looks reasonable to me. Acked-by: Kirill A. Shutemov <[email protected]> madvise(MADV_DONTNEED) was aproblematic with THP before. Is a big win having mmap_sem taken on read rather than on write for it? -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
