Messages in this thread |  | | Subject | Re: [RFC v6 PATCH 1/2] mm: refactor do_munmap() to extract the common part | From | Yang Shi <> | Date | Tue, 7 Aug 2018 11:06:01 -0700 |
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On 8/7/18 7:59 AM, Vlastimil Babka wrote: > On 07/26/2018 08:10 PM, Yang Shi wrote: >> Introduces three new helper functions: >> * munmap_addr_sanity() >> * munmap_lookup_vma() >> * munmap_mlock_vma() >> >> They will be used by do_munmap() and the new do_munmap with zapping >> large mapping early in the later patch. >> >> There is no functional change, just code refactor. >> >> Reviewed-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> >> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> >> --- >> mm/mmap.c | 120 ++++++++++++++++++++++++++++++++++++++++++-------------------- >> 1 file changed, 82 insertions(+), 38 deletions(-) >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index d1eb87e..2504094 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -2686,34 +2686,44 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, >> return __split_vma(mm, vma, addr, new_below); >> } >> >> -/* Munmap is split into 2 main parts -- this part which finds >> - * what needs doing, and the areas themselves, which do the >> - * work. This now handles partial unmappings. >> - * Jeremy Fitzhardinge <jeremy@goop.org> >> - */ >> -int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, >> - struct list_head *uf) >> +static inline bool munmap_addr_sanity(unsigned long start, size_t len) > Since it's returning bool, the proper naming scheme would be something > like "munmap_addr_ok()". I don't know how I would replace the "munmap_" > prefix myself though.
OK, thanks for the suggestion.
> >> { >> - unsigned long end; >> - struct vm_area_struct *vma, *prev, *last; >> - >> if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) >> - return -EINVAL; >> + return false; >> >> - len = PAGE_ALIGN(len); >> - if (len == 0) >> - return -EINVAL; >> + if (PAGE_ALIGN(len) == 0) >> + return false; >> + >> + return true; >> +} >> + >> +/* >> + * munmap_lookup_vma: find the first overlap vma and split overlap vmas. >> + * @mm: mm_struct >> + * @vma: the first overlapping vma >> + * @prev: vma's prev >> + * @start: start address >> + * @end: end address >> + * >> + * returns 1 if successful, 0 or errno otherwise >> + */ >> +static int munmap_lookup_vma(struct mm_struct *mm, struct vm_area_struct **vma, >> + struct vm_area_struct **prev, unsigned long start, >> + unsigned long end) > Agree with Michal that you could simply return vma, NULL, or error. > Caller can easily find out prev from that, it's not like we have to > count each cpu cycle here. It will be a bit less tricky code as well, > which is a plus. > > ... >> +static inline void munmap_mlock_vma(struct vm_area_struct *vma, >> + unsigned long end) > This function does munlock, not mlock. You could call it e.g. > munlock_vmas().
OK
> >> +{ >> + struct vm_area_struct *tmp = vma; >> + >> + while (tmp && tmp->vm_start < end) { >> + if (tmp->vm_flags & VM_LOCKED) { >> + vma->vm_mm->locked_vm -= vma_pages(tmp); > You keep 'vma' just for the vm_mm? Better extract mm pointer first and > then you don't need the 'tmp'.
OK
Thanks, Yang
> >> + munlock_vma_pages_all(tmp); >> + } >> + tmp = tmp->vm_next; >> + } >> +}
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