| Message ID | 1531956101-8526-2-git-send-email-yang.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 19/07/2018 01:21, 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. > > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> FWIW : Reviewed-by : Laurent Dufour <ldufour@linux.vnet.ibm.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) > { > - 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) > +{ > + struct vm_area_struct *tmp, *last; > > /* Find the first overlapping VMA */ > - vma = find_vma(mm, start); > - if (!vma) > + tmp = find_vma(mm, start); > + if (!tmp) > return 0; > - prev = vma->vm_prev; > - /* we have start < vma->vm_end */ > + > + *prev = tmp->vm_prev; > + > + /* we have start < vma->vm_end */ > > /* if it doesn't overlap, we have nothing.. */ > - end = start + len; > - if (vma->vm_start >= end) > + if (tmp->vm_start >= end) > return 0; > > /* > @@ -2723,7 +2733,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, > * unmapped vm_area_struct will remain in use: so lower split_vma > * places tmp vma above, and higher split_vma places tmp vma below. > */ > - if (start > vma->vm_start) { > + if (start > tmp->vm_start) { > int error; > > /* > @@ -2731,13 +2741,14 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, > * not exceed its limit; but let map_count go just above > * its limit temporarily, to help free resources as expected. > */ > - if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) > + if (end < tmp->vm_end && > + mm->map_count > sysctl_max_map_count) > return -ENOMEM; > > - error = __split_vma(mm, vma, start, 0); > + error = __split_vma(mm, tmp, start, 0); > if (error) > return error; > - prev = vma; > + *prev = tmp; > } > > /* Does it split the last one? */ > @@ -2747,7 +2758,48 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, > if (error) > return error; > } > - vma = prev ? prev->vm_next : mm->mmap; > + > + *vma = *prev ? (*prev)->vm_next : mm->mmap; > + > + return 1; > +} > + > +static inline void munmap_mlock_vma(struct vm_area_struct *vma, > + unsigned long end) > +{ > + 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); > + munlock_vma_pages_all(tmp); > + } > + tmp = tmp->vm_next; > + } > +} > + > +/* 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) > +{ > + unsigned long end; > + struct vm_area_struct *vma = NULL, *prev; > + int ret = 0; > + > + if (!munmap_addr_sanity(start, len)) > + return -EINVAL; > + > + len = PAGE_ALIGN(len); > + > + end = start + len; > + > + ret = munmap_lookup_vma(mm, &vma, &prev, start, end); > + if (ret != 1) > + return ret; > > if (unlikely(uf)) { > /* > @@ -2759,24 +2811,16 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, > * split, despite we could. This is unlikely enough > * failure that it's not worth optimizing it for. > */ > - int error = userfaultfd_unmap_prep(vma, start, end, uf); > - if (error) > - return error; > + ret = userfaultfd_unmap_prep(vma, start, end, uf); > + if (ret) > + return ret; > } > > /* > * unlock any mlock()ed ranges before detaching vmas > */ > - if (mm->locked_vm) { > - struct vm_area_struct *tmp = vma; > - while (tmp && tmp->vm_start < end) { > - if (tmp->vm_flags & VM_LOCKED) { > - mm->locked_vm -= vma_pages(tmp); > - munlock_vma_pages_all(tmp); > - } > - tmp = tmp->vm_next; > - } > - } > + if (mm->locked_vm) > + munmap_mlock_vma(vma, end); > > /* > * Remove the vma's, and unmap the actual pages >
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) { - 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) +{ + struct vm_area_struct *tmp, *last; /* Find the first overlapping VMA */ - vma = find_vma(mm, start); - if (!vma) + tmp = find_vma(mm, start); + if (!tmp) return 0; - prev = vma->vm_prev; - /* we have start < vma->vm_end */ + + *prev = tmp->vm_prev; + + /* we have start < vma->vm_end */ /* if it doesn't overlap, we have nothing.. */ - end = start + len; - if (vma->vm_start >= end) + if (tmp->vm_start >= end) return 0; /* @@ -2723,7 +2733,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * unmapped vm_area_struct will remain in use: so lower split_vma * places tmp vma above, and higher split_vma places tmp vma below. */ - if (start > vma->vm_start) { + if (start > tmp->vm_start) { int error; /* @@ -2731,13 +2741,14 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * not exceed its limit; but let map_count go just above * its limit temporarily, to help free resources as expected. */ - if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) + if (end < tmp->vm_end && + mm->map_count > sysctl_max_map_count) return -ENOMEM; - error = __split_vma(mm, vma, start, 0); + error = __split_vma(mm, tmp, start, 0); if (error) return error; - prev = vma; + *prev = tmp; } /* Does it split the last one? */ @@ -2747,7 +2758,48 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, if (error) return error; } - vma = prev ? prev->vm_next : mm->mmap; + + *vma = *prev ? (*prev)->vm_next : mm->mmap; + + return 1; +} + +static inline void munmap_mlock_vma(struct vm_area_struct *vma, + unsigned long end) +{ + 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); + munlock_vma_pages_all(tmp); + } + tmp = tmp->vm_next; + } +} + +/* 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) +{ + unsigned long end; + struct vm_area_struct *vma = NULL, *prev; + int ret = 0; + + if (!munmap_addr_sanity(start, len)) + return -EINVAL; + + len = PAGE_ALIGN(len); + + end = start + len; + + ret = munmap_lookup_vma(mm, &vma, &prev, start, end); + if (ret != 1) + return ret; if (unlikely(uf)) { /* @@ -2759,24 +2811,16 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * split, despite we could. This is unlikely enough * failure that it's not worth optimizing it for. */ - int error = userfaultfd_unmap_prep(vma, start, end, uf); - if (error) - return error; + ret = userfaultfd_unmap_prep(vma, start, end, uf); + if (ret) + return ret; } /* * unlock any mlock()ed ranges before detaching vmas */ - if (mm->locked_vm) { - struct vm_area_struct *tmp = vma; - while (tmp && tmp->vm_start < end) { - if (tmp->vm_flags & VM_LOCKED) { - mm->locked_vm -= vma_pages(tmp); - munlock_vma_pages_all(tmp); - } - tmp = tmp->vm_next; - } - } + if (mm->locked_vm) + munmap_mlock_vma(vma, end); /* * Remove the vma's, and unmap the actual pages
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. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> --- mm/mmap.c | 120 ++++++++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 82 insertions(+), 38 deletions(-)