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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: z8kxkg99oe9abnocjxmjc54ongbtynfr X-Rspam-User: X-Rspamd-Queue-Id: B7F501C0006 X-HE-Tag: 1743607178-727288 X-HE-Meta: U2FsdGVkX1+tzv088QWmFpcd/VmKZw8N8NNnixe91sGbH7LJ+Pp3MT6V25rQpnnySzk0AJaaZAlJt2NMOjqMZWMBq6Uloeq0jhUWDwecQ5cpaXnVVXlEHRgwj2h/ALgVBHEqeNhig9ZHM01Q/EkRLTQO1NDm4ktvLarW2ab6/axoT8FBu7Jk1tb/zx9C2xPiMT7gOe/Z5Z78ryc7oX98KKlZY5jG+e5gjyC/MqbL4ZndYTpC5Qwg3KJadbzUlnEy1JfeE1/T+93TfhiiibXoSf3mYYkMVW6lE0Sk1PNOvEBXuKWRWDHmhwyg2J3IJzlfA+jaLGW6LEcsxZtUisef1yV2204YfcTnO0NJ/QOnO4v9ccmHu61MGFXJYgi5x8O3hhXSo910TUvfizZmqKLwQIAVQ98WFIE83pwSHWgskap4V8DZcaWLnqnX1bWCIVFJFMUDgON1ScolgB9lmOdKl0SXexGcxaYdZQeN11mbZ1jPixkLetWhakKQWreYjS0QDQGOS7LBdYeMFPSw7PSdQMhQ1RlcstOBLx5aQY0L5mmgA+c0oKadKcSdwadvVxWlkg2R1GsGA07OgYJM0wluLib2bcKz5yQhsXvxvKi3ZII3KImmTzBY3Gm+bTlNowuZ/FwZhV+Xd33JoD7cX9jyh33P/NaKF7FvvdOmtpShrbswn2g5eS4DmwCLC1k4pdISae+gnguk0z9tyoJ6dcsaqjRQiZw70Zu/NwIooecRJwl+KP4eDe30XNv0BFYmObR2D3IAmzq2e/WmMGWy0qoR0Nm3h/oL4yCCAyhVvswgDH88yA3IZi9dsb2JJa50W65DtEOJY3Zn6ut1C7f1fdgHfKSnqHQP2fp68lgcGMTMBo0LA+rEQrBsiVlUweM8wLHSNcI8nKfna3i6RIbOj/fdw8lD2qoFcwv0VrOQYC1T9N76YqMlbQfGrBHBj5L/aTftI/bHC/a1Xx8PBnFOOWV Snb59wsK l2cuIdy5pOomvcjPElMtA85VJ+u09m7OjKkkBnHCCP6cjP7/i4xjR0q82xuSOhpH7IC/9DOPask72fHY0mn8RfKaQwdHXCf8nk7j3mChtiAV0FjL4AZNGot1HFm8wJaIJsbXhal5h9Jp+EvsQo/FJ7vQhrLyVhp9l0scIbQ1nHz0hp+Vvd+CX6db60pRthKNhjqNAMM0wZoNUzYC/kKrDfbqBXBOhM/3ohN8ioiTbhG0JMuiSLRb9d4ymTdjwaefnyKDgPDAwvB3pbjx+XUXgm/51NLQ4hTTSbZhwOFmk/90MCCr/hcZYiu9K/N2sNC3911rKoWtHPIU7N4d+vZYSiEecllQzSuz/BNE8+5B2QXRz0tHrHjN8qLz8djzl0fQq6T58TlCy1EwY5bZmETCWlDxI5ZG/tMJbnbuv53kgI/YmTIo22jXR/qwRj2BE0ajpqB9CdjK6Tf5tvf8= 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 02.04.25 14:31, Lorenzo Stoakes wrote: > TL;DR is I agree with you :P I'm not sure where to put R-b tag given you sent a > fix-patch, as this is obviously smatch/clang-broken as-is so feels wrong to put > on main bit. I'll respin! :) > > I guess I'll put on fix-patch and Andrew? Are you taking this? If so maybe from > there you can propagate? [...] > > If that handles it then fine, let's just init to 0. > >> >> So this should be working as expected? No need to add something on top that >> makes it even more ugly in the caller. > > Yes, agreed, if this is already being handled in the one hideous place let's > make it hideous there only. > > But maybe a comment...? I can add that that function handles the need for actual untracking internally. [...] >>>> + >>>> + /* >>>> + * Duplicate the PAT information for the dst VMA based on the src >>>> + * VMA. >>>> + */ >>>> + if (get_pat_info(src_vma, &paddr, &pgprot)) >>>> + return -EINVAL; >>>> + rc = reserve_pfn_range(paddr, vma_size, &pgprot, 1); >>>> + if (rc) >>>> + return rc; >>> >>> I mean it's a crazy nit, but we use ret elsewhere but rc here, maybe better >>> to use ret in both places. >>> >>> But also feel free to ignore this. >> >> "int retval;" ? ;) > > Lol, 'rv'? > > Maybe let's leave it as is :P I think "ret" is used in the file, so I'll use that. > >> >>> >>>> >>>> + /* Reservation for the destination VMA succeeded. */ >>>> + vm_flags_set(dst_vma, VM_PAT); >>>> + *pfn = PHYS_PFN(paddr); >>>> return 0; >>>> } >>>> >>>> +void untrack_pfn_copy(struct vm_area_struct *dst_vma, unsigned long pfn) >>>> +{ >>>> + untrack_pfn(dst_vma, pfn, dst_vma->vm_end - dst_vma->vm_start, true); >>>> + /* >>>> + * Reservation was freed, any copied page tables will get cleaned >>>> + * up later, but without getting PAT involved again. >>>> + */ >>>> +} >>>> + >>>> /* >>>> * prot is passed in as a parameter for the new mapping. If the vma has >>>> * a linear pfn mapping for the entire range, or no vma is provided, >>>> @@ -1095,15 +1108,6 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, >>>> } >>>> } >>>> >>>> -/* >>>> - * untrack_pfn_clear is called if the following situation fits: >>>> - * >>>> - * 1) while mremapping a pfnmap for a new region, with the old vma after >>>> - * its pfnmap page table has been removed. The new vma has a new pfnmap >>>> - * to the same pfn & cache type with VM_PAT set. >>>> - * 2) while duplicating vm area, the new vma fails to copy the pgtable from >>>> - * old vma. >>>> - */ >>> >>> This just wrong now? >> >> Note that I'm keeping the doc to a single place -- the stub in the header. >> (below) >> >> Or can you elaborate what exactly is "wrong"? > > Ah ok maybe I just missed this. I was asking whether it was wrong, and this is > why maybe you are removing (perhaps, not very clearly :) Ah, sorry. Yes, it's just deduplicated to be adjusted in the other copy :) [...] >>> Can I say as an aside that I hate this kind of hook? Like quite a lot? >>> >>> I mean I've been looking at mremap() of anon mappings as you know obv. but >>> the thought of PFN mapping mremap()ing is kind of also a bit ugh. >> >> I absolutely hate all of that, but I'll have to leave any cleanups to people >> with more spare time ;) > > Lol well... maybe at some point I will find some for this... when things get > ugly enough I find that I make the time in the end ;) We're kind-of attaching metadata to a VMA, that is not directly linked to the VMA. And the duplication of a VMA cannot handle that, so we defer copying of that metadata. Hm ... -- Cheers, David / dhildenb