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charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 24 Jan 2022, at 13:11, David Rientjes wrote: > On Mon, 24 Jan 2022, Muchun Song wrote: > >> The D-cache maintenance inside move_to_new_page() only consider one pa= ge, >> there is still D-cache maintenance issue for tail pages of THP. Fix th= is >> by not using flush_dcache_folio() since it is not backportable. >> > > The mention of being backportable suggests that we should backport this= , > likely to 4.14+. So should it be marked as stable? Hmm, after more digging, I am not sure if the bug exists. For THP migrati= on, flush_cache_range() is used in remove_migration_pmd(). The flush_dcache_p= age() was added by Lars Persson (cc=E2=80=99d) to solve the data corruption on = MIPS[1], but THP migration is only enabled on x86_64, PPC_BOOK3S_64, and ARM64. To make code more consistent, I guess flush_cache_range() in remove_migra= tion_pmd() can be removed, since it is superseded by the flush_dcache_page() below. The Fixes can be dropped. Let me know if I miss anything. > > That aside, should there be a follow-up patch that converts to using > flush_dcache_folio()? Are you suggesting to convert just this code or the entire move_to_new_pa= ge() to use folio? The latter might be more desirable, since the code will be more consistent. [1] https://lore.kernel.org/all/20190315083502.11849-1-larper@axis.com/T/= #u > >> Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path") >> Signed-off-by: Muchun Song >> --- >> Changes in v2: >> - Using a for loop instead of the folio variant for backportable. >> >> mm/migrate.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index c9296d63878d..c418e8d92b9c 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -933,9 +933,12 @@ static int move_to_new_page(struct page *newpage,= struct page *page, >> if (!PageMappingFlags(page)) >> page->mapping =3D NULL; >> >> - if (likely(!is_zone_device_page(newpage))) >> - flush_dcache_page(newpage); >> + if (likely(!is_zone_device_page(newpage))) { >> + int i, nr =3D compound_nr(newpage); >> >> + for (i =3D 0; i < nr; i++) >> + flush_dcache_page(newpage + i); >> + } >> } >> out: >> return rc; >> -- = >> 2.11.0 >> >> >> -- Best Regards, Yan, Zi --=_MailMate_66E87597-6A15-453E-97BD-4AB79E478476_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmHu/HkPHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqKX3wP/2U0E8oTmNPe6nFtlMTzKDK1Lr/4Vi/uh39a e97o78hnPqD2PiAPxenBMq3pDxZN+qcJMWeXSATr+UJWiY6Nh4q6Bfeghv2rbtO7 xIMP1AlH6jcpi+xVBRqwp1hdgUE41V2vhhMhhLdhA751smyxn7icqo/LpkOaiRKZ DZ4pj4oLE7g1atFTeQz0hwySUwf296p7hXareJxb7GRf58sVdkNMY/IZzqdrmR+S joofnio1Hda8kVNCxEDsoFYfdnSHUD9UQL607Rq+3TFJiDA81ZMdW83/cRjhx2Qv zM9AiMH3g4yTHFTSH+yRCrdsgmQtEThttRlI97fU9p6C2yDKJpCV3+uTnCcUCxIg 5clauciRzgvUjqs9AYqwaQtjypD4ISYjwbt2YMTbPfkG1ucSO5vAA3hFJepTvd/D zFCE52P3iq2Qogw+lquj3FenHizbbySeyiDW0qCWTzJLASFyp75rpGVOgXzglQgr bmpRc29yI+MpysLHJh/XH8jjArvkYz7s5X8uqUB9c28ltEf1zuOJGUpj4b5gG/2c SQZzGqPSDa2J9R/jaZZopX7aBe9fJvF2h2UrDB5cffR9fxsy8GixcgtAJv0aMs2h HoQS7tzFdXddP6msAvuSv9kMzcBqornJiyS6KaLnzHu3j46o5EQLY1Z8hfe+1AVB qvKYHjEf =NQ+Z -----END PGP SIGNATURE----- --=_MailMate_66E87597-6A15-453E-97BD-4AB79E478476_=--