Message ID | 20220621204632.3370049-1-Liam.Howlett@oracle.com (mailing list archive) |
---|---|
Headers | show |
Series | Introducing the Maple Tree | expand |
On 21.06.22 22:46, Liam Howlett wrote: > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > Using the maple tree interface mt_find() will handle the RCU locking and > will start searching at the address up to the limit, ULONG_MAX in this > case. > > Add kernel documentation to this API. > > Link: https://lkml.kernel.org/r/20220504010716.661115-13-Liam.Howlett@oracle.com > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > Acked-by: Vlastimil Babka <vbabka@suse.cz> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: David Howells <dhowells@redhat.com> > Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> > Cc: SeongJae Park <sj@kernel.org> > Cc: Will Deacon <will@kernel.org> > Cc: Davidlohr Bueso <dave@stgolabs.net> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > mm/mmap.c | 28 ++++++++++------------------ > 1 file changed, 10 insertions(+), 18 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index d7e6baa2f40f..fdb61252448f 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -2486,11 +2486,18 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, > > EXPORT_SYMBOL(get_unmapped_area); > > -/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ > +/** > + * find_vma() - Find the VMA for a given address, or the next vma. > + * @mm: The mm_struct to check > + * @addr: The address > + * > + * Returns: The VMA associated with addr, or the next vma. > + * May return %NULL in the case of no vma at addr or above. Nit: inconsistent use of VMA vs. vma. > + */ > struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) > { > - struct rb_node *rb_node; > struct vm_area_struct *vma; > + unsigned long index = addr; > > mmap_assert_locked(mm); > /* Check the cache first. */ > @@ -2498,22 +2505,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) > if (likely(vma)) > return vma; > > - rb_node = mm->mm_rb.rb_node; > - > - while (rb_node) { > - struct vm_area_struct *tmp; > - > - tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); > - > - if (tmp->vm_end > addr) { > - vma = tmp; > - if (tmp->vm_start <= addr) > - break; > - rb_node = rb_node->rb_left; > - } else > - rb_node = rb_node->rb_right; > - } > - > + vma = mt_find(&mm->mm_mt, &index, ULONG_MAX); I guess it would be handy to have a mt_find() variant that simply consumes an address, because for example here, we don't actually care about the output semantics? Does anything speak against such a utility function or is this here really just a corner case? That would make that code *even easier* to read. > if (vma) > vmacache_update(addr, vma); > return vma; Reviewed-by: David Hildenbrand <david@redhat.com>
On 21.06.22 22:46, Liam Howlett wrote: > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > This simplifies the implementation and is faster than using the linked > list. > > Link: https://lkml.kernel.org/r/20220504010716.661115-12-Liam.Howlett@oracle.com > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > Acked-by: Vlastimil Babka <vbabka@suse.cz> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: David Howells <dhowells@redhat.com> > Cc: SeongJae Park <sj@kernel.org> > Cc: Will Deacon <will@kernel.org> > Cc: Davidlohr Bueso <dave@stgolabs.net> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > mm/mmap.c | 24 +++++++----------------- > 1 file changed, 7 insertions(+), 17 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 6be7833c781b..d7e6baa2f40f 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -675,29 +675,19 @@ munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len, > > return 0; > } > + > static unsigned long count_vma_pages_range(struct mm_struct *mm, > unsigned long addr, unsigned long end) > { > - unsigned long nr_pages = 0; > + VMA_ITERATOR(vmi, mm, addr); > struct vm_area_struct *vma; > + unsigned long nr_pages = 0; > > - /* Find first overlapping mapping */ > - vma = find_vma_intersection(mm, addr, end); > - if (!vma) > - return 0; > - > - nr_pages = (min(end, vma->vm_end) - > - max(addr, vma->vm_start)) >> PAGE_SHIFT; > - > - /* Iterate over the rest of the overlaps */ > - for (vma = vma->vm_next; vma; vma = vma->vm_next) { > - unsigned long overlap_len; > - > - if (vma->vm_start > end) > - break; > + for_each_vma_range(vmi, vma, end) { > + unsigned long vm_start = max(addr, vma->vm_start); > + unsigned long vm_end = min(end, vma->vm_end); I thought using max_t and min_t was the latest advisory. I might be wrong and simply kept doing it that way ;) > > - overlap_len = min(end, vma->vm_end) - vma->vm_start; > - nr_pages += overlap_len >> PAGE_SHIFT; > + nr_pages += (vm_end - vm_start) / PAGE_SIZE; PHYS_PFN(vm_end - vm_start) > } > > return nr_pages; Reviewed-by: David Hildenbrand <david@redhat.com>
* David Hildenbrand <david@redhat.com> [220621 17:04]: > On 21.06.22 22:46, Liam Howlett wrote: > > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > > > Using the maple tree interface mt_find() will handle the RCU locking and > > will start searching at the address up to the limit, ULONG_MAX in this > > case. > > > > Add kernel documentation to this API. > > > > Link: https://lkml.kernel.org/r/20220504010716.661115-13-Liam.Howlett@oracle.com > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > > Acked-by: Vlastimil Babka <vbabka@suse.cz> > > Cc: Catalin Marinas <catalin.marinas@arm.com> > > Cc: David Howells <dhowells@redhat.com> > > Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > Cc: SeongJae Park <sj@kernel.org> > > Cc: Will Deacon <will@kernel.org> > > Cc: Davidlohr Bueso <dave@stgolabs.net> > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > --- > > mm/mmap.c | 28 ++++++++++------------------ > > 1 file changed, 10 insertions(+), 18 deletions(-) > > > > diff --git a/mm/mmap.c b/mm/mmap.c > > index d7e6baa2f40f..fdb61252448f 100644 > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -2486,11 +2486,18 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, > > > > EXPORT_SYMBOL(get_unmapped_area); > > > > -/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ > > +/** > > + * find_vma() - Find the VMA for a given address, or the next vma. > > + * @mm: The mm_struct to check > > + * @addr: The address > > + * > > + * Returns: The VMA associated with addr, or the next vma. > > + * May return %NULL in the case of no vma at addr or above. > > Nit: inconsistent use of VMA vs. vma. I'll update the comment. > > > + */ > > struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) > > { > > - struct rb_node *rb_node; > > struct vm_area_struct *vma; > > + unsigned long index = addr; > > > > mmap_assert_locked(mm); > > /* Check the cache first. */ > > @@ -2498,22 +2505,7 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) > > if (likely(vma)) > > return vma; > > > > - rb_node = mm->mm_rb.rb_node; > > - > > - while (rb_node) { > > - struct vm_area_struct *tmp; > > - > > - tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); > > - > > - if (tmp->vm_end > addr) { > > - vma = tmp; > > - if (tmp->vm_start <= addr) > > - break; > > - rb_node = rb_node->rb_left; > > - } else > > - rb_node = rb_node->rb_right; > > - } > > - > > + vma = mt_find(&mm->mm_mt, &index, ULONG_MAX); > > I guess it would be handy to have a mt_find() variant that simply > consumes an address, because for example here, we don't actually care > about the output semantics? Does anything speak against such a utility > function or is this here really just a corner case? > > That would make that code *even easier* to read. That makes sense. I just don't want to have a whole lot of APIs that do the same thing. I'll add it to my list and see how often we see the pattern though. > > > if (vma) > > vmacache_update(addr, vma); > > return vma; > > Reviewed-by: David Hildenbrand <david@redhat.com> > > -- > Thanks, > > David / dhildenb >
* David Hildenbrand <david@redhat.com> [220621 17:13]: > On 21.06.22 22:46, Liam Howlett wrote: > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > This simplifies the implementation and is faster than using the linked > > list. > > > > Link: https://lkml.kernel.org/r/20220504010716.661115-12-Liam.Howlett@oracle.com > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > > Acked-by: Vlastimil Babka <vbabka@suse.cz> > > Cc: Catalin Marinas <catalin.marinas@arm.com> > > Cc: David Howells <dhowells@redhat.com> > > Cc: SeongJae Park <sj@kernel.org> > > Cc: Will Deacon <will@kernel.org> > > Cc: Davidlohr Bueso <dave@stgolabs.net> > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > --- > > mm/mmap.c | 24 +++++++----------------- > > 1 file changed, 7 insertions(+), 17 deletions(-) > > > > diff --git a/mm/mmap.c b/mm/mmap.c > > index 6be7833c781b..d7e6baa2f40f 100644 > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -675,29 +675,19 @@ munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len, > > > > return 0; > > } > > + > > static unsigned long count_vma_pages_range(struct mm_struct *mm, > > unsigned long addr, unsigned long end) > > { > > - unsigned long nr_pages = 0; > > + VMA_ITERATOR(vmi, mm, addr); > > struct vm_area_struct *vma; > > + unsigned long nr_pages = 0; > > > > - /* Find first overlapping mapping */ > > - vma = find_vma_intersection(mm, addr, end); > > - if (!vma) > > - return 0; > > - > > - nr_pages = (min(end, vma->vm_end) - > > - max(addr, vma->vm_start)) >> PAGE_SHIFT; > > - > > - /* Iterate over the rest of the overlaps */ > > - for (vma = vma->vm_next; vma; vma = vma->vm_next) { > > - unsigned long overlap_len; > > - > > - if (vma->vm_start > end) > > - break; > > + for_each_vma_range(vmi, vma, end) { > > + unsigned long vm_start = max(addr, vma->vm_start); > > + unsigned long vm_end = min(end, vma->vm_end); > > I thought using max_t and min_t was the latest advisory. I might be > wrong and simply kept doing it that way ;) They are the same type so I think this is okay. > > > > > - overlap_len = min(end, vma->vm_end) - vma->vm_start; > > - nr_pages += overlap_len >> PAGE_SHIFT; > > + nr_pages += (vm_end - vm_start) / PAGE_SIZE; > > PHYS_PFN(vm_end - vm_start) > > > } > > > > return nr_pages; > > Reviewed-by: David Hildenbrand <david@redhat.com> > > -- > Thanks, > > David / dhildenb >