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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: f4wwwt8dyucsit3rcpf5kxn814kh9od8 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7A53E140003 X-HE-Tag: 1747677867-655624 X-HE-Meta: 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 dEEwcbGv wVvuWHuQE7vW1+qB2VzlJtDbqB9a2U508DQy+qODl06VOE/HaoUD9LtcRLHmCU+YV9pMZrQ1Wl+QML4Eq2+iihRSLbxJZJ/OToUchmYh+rh6J9cCOD92wiAc+Wu+MB8fW1ja1dB+N3T3xAibpckE6209+jjBVIo4uh6ddU44tzImzWQeSgqHTjMdpDezw410xgh+tXpBTsh2X84v+ygXI3soBnLTldj0uv3W0PBDlgHGrJqn6jvQHlIoqcD+oAx/Hg2PYoaaC6uEAPDcPfcH+woffhao4g2noJfJyXDAUy0US8p+bjCXjZGuI6+dxmSYHAztlxg9YQ3PRj3LdZUeJ6vAr/gH4YmjM61zJaFcdMs1vXtckllmhxB7cYTgeF+XPx/hCX7lKVSOsuYiWCPnAekE4zg== 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: >> +/* >> + * Are we guaranteed no driver can change state such as to preclude KSM merging? >> + * If so, let's set the KSM mergeable flag early so we don't break VMA merging. >> + * >> + * This is applicable when PR_SET_MEMORY_MERGE has been set on the mm_struct via >> + * prctl() causing newly mapped VMAs to have the KSM mergeable VMA flag set. >> + * >> + * If this is not the case, then we set the flag after considering mergeability, >> + * which will prevent mergeability as, when PR_SET_MEMORY_MERGE is set, a new >> + * VMA will not have the KSM mergeability VMA flag set, but all other VMAs will, >> + * preventing any merge. > > Hmmm, so an ordinary MAP_PRIVATE of any file (executable etc.) will get > VM_MERGEABLE set but not be able to merge? > > Probably these are not often expected to be merged ... > > Preventing merging should really only happen because of VMA flags that > are getting set: VM_PFNMAP, VM_MIXEDMAP, VM_DONTEXPAND, VM_IO. > > > I am not 100% sure why we bail out on special mappings: all we have to > do is reliably identify anon pages, and we should be able to do that. > > GUP does currently refuses any VM_PFNMAP | VM_IO, and KSM uses GUP, > which might need a tweak then (maybe the solution could be to ... not > use GUP but a folio_walk). Oh, someone called "David" already did that. Nice :) So we *should* be able to drop * VM_PFNMAP: we correctly identify CoWed pages * VM_MIXEDMAP: we correctly identify CoWed pages * VM_IO: should not affect CoWed pages * VM_DONTEXPAND: no idea why that should even matter here -- Cheers, David / dhildenb