• Kirill A. Shutemov's avatar
    mm, thp: Do not make pmd/pud dirty without a reason · 152e93af
    Kirill A. Shutemov authored
    Currently we make page table entries dirty all the time regardless of
    access type and don't even consider if the mapping is write-protected.
    The reasoning is that we don't really need dirty tracking on THP and
    making the entry dirty upfront may save some time on first write to the
    Unfortunately, such approach may result in false-positive
    can_follow_write_pmd() for huge zero page or read-only shmem file.
    Let's only make page dirty only if we about to write to the page anyway
    (as we do for small pages).
    I've restructured the code to make entry dirty inside
    maybe_p[mu]d_mkwrite(). It also takes into account if the vma is
    Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Cc: Hugh Dickins <hughd@google.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
huge_memory.c 81.3 KB