Messages in this thread | | | Date | Mon, 24 Aug 2009 13:13:56 +0900 | Subject | Re: [PATCH] mm: make munlock fast when mlock is canceled by sigkill | From | KOSAKI Motohiro <> |
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> This patch is for making commit 4779280d1e (mm: make get_user_pages() > interruptible) complete.
Yes. commit 4779280d1e (mm: make get_user_pages() interruptible) has never works as expected since it's born. IOW, it was totally broken.
This patch is definitely good forward step patch.
>> > @@ -254,6 +254,7 @@ static inline void >> > mminit_validate_memmodel_limits(unsigned long *start_pfn, >> > #define GUP_FLAGS_FORCE 0x2 >> > #define GUP_FLAGS_IGNORE_VMA_PERMISSIONS 0x4 >> > #define GUP_FLAGS_IGNORE_SIGKILL 0x8 >> > +#define GUP_FLAGS_ALLOW_NULL 0x10 >> > >> >> I am worried about adding new flag whenever we need it. >> But I think this case makes sense to me. >> In addition, I guess ZERO page can also use this flag. >> >> Kame. What do you think about it? >> > I do welcome this ! > Then, I don't have to take care of mlock/munlock in ZERO_PAGE patch. > > And without this patch, munlock() does copy-on-write just for unpinning memory. > So, this patch shows some right direction, I think. > > One concern is flag name, ALLOW_NULL sounds not very good. > > GUP_FLAGS_NOFAULT ? > > I wonder we can remove a hack of FOLL_ANON for core-dump by this flag, too.
Yeah, GUP_FLAGS_NOFAULT is better.
Plus, this patch change __get_user_pages() return value meaning IOW. after this patch, it can return following value,
return value: 3 pages[0]: hoge-page pages[1]: null pages[2]: fuga-page
but, it can be
return value: 2 pages[0]: hoge-page pages[1]: fuga-page
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