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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 0242818000A X-Stat-Signature: hbg7dmqzynjwknht43q9p4d8o5p9jkww X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1759552938-714049 X-HE-Meta: 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 VNbjPWDg su/W9oZsnhracLEmwqltQm6MMXq3DqAMsgnJNcI91tr1k9NwGhAbNfH14lY24mcosaN2juXD/4069sOg4BS06vuRTWHQvQpv5ssAKeUD6P9Wa9zlCjn6PZGIqi12mk55Dwts9dfHYWLH1MSGkbcJQr65lZkjm5Ng2B3QtblFAnmHt1wIB7+e2l63Hsy1Hxsk6SqWvKDDFi/rw7wyxhvjcO+7Tgolvvomg3BDGNo44wX6tvraMksk52p2j5Y/4kTq6DTKFemOp7aor7dg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/10/25 8:33 am, Lance Yang wrote: > > > On 2025/10/4 01:05, Dev Jain wrote: >> >> On 02/10/25 1:02 pm, Lance Yang wrote: >>> From: Lance Yang >>> >>> As David suggested, the PTE scanning logic in hpage_collapse_scan_pmd() >>> and __collapse_huge_page_isolate() was almost duplicated. >>> >>> This patch cleans things up by moving all the common PTE checking logic >>> into a new shared helper, thp_collapse_check_pte(). >>> >>> Suggested-by: David Hildenbrand >>> Signed-off-by: Lance Yang >>> --- >> >> In hpage_collapse_scan_pmd(), we enter with mmap lock held, so for >> an anonymous vma, is it even possible to hit if >> (!folio_test_anon(folio))? > > Ah, indeed :) > >> In which case we can replace this with VM_BUG_ON_FOLIO and abstract away >> till the folio_maybe_mapped_shared() block? > > So you meant something like this: > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 2a897cfb1d03..ef87d7fe3d50 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1374,11 +1374,7 @@ static int hpage_collapse_scan_pmd(struct > mm_struct *mm, >                         goto out_unmap; >                 } >                 folio = page_folio(page); > - > -               if (!folio_test_anon(folio)) { > -                       result = SCAN_PAGE_ANON; > -                       goto out_unmap; > -               } > +               VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); Yes, I would suggest a different patch making this change, then in the last patch you can abstract away till the shared statistics line since that much code will become common between scan_pmd and _isolate. > >                 /* >                  * We treat a single page as shared if any part of the > THP > >