| Message ID | 20200828081031.11306-1-richard.weiyang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/mmap: leave adjust_next as virtual address instead of page frame number | expand |
On 8/28/20 10:10 AM, Wei Yang wrote: > Instead of convert adjust_next between virtual address and page frame > number, let's just store the virtual address into adjust_next. IMHO more precisely/less confusing it's "bytes" and "pages" instead of "virtual address" (which is absolute address, but this variable holds a difference) and "page frame number" (which is related to absolute physical address, but what we have is difference in pages in virtual address space). > Also, this patch fixes one typo in the comment of > vma_adjust_trans_huge(). > > Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com> Other than that, seems like it leads to less shifting, so Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/huge_memory.c | 4 ++-- > mm/mmap.c | 8 ++++---- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 78c84bee7e29..2c633ba14440 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2300,13 +2300,13 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma, > > /* > * If we're also updating the vma->vm_next->vm_start, if the new > - * vm_next->vm_start isn't page aligned and it could previously > + * vm_next->vm_start isn't hpage aligned and it could previously > * contain an hugepage: check if we need to split an huge pmd. > */ > if (adjust_next > 0) { > struct vm_area_struct *next = vma->vm_next; > unsigned long nstart = next->vm_start; > - nstart += adjust_next << PAGE_SHIFT; > + nstart += adjust_next; > if (nstart & ~HPAGE_PMD_MASK && > (nstart & HPAGE_PMD_MASK) >= next->vm_start && > (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) > diff --git a/mm/mmap.c b/mm/mmap.c > index 90b1298d4222..e4c9bbfd4103 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -758,7 +758,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, > * vma expands, overlapping part of the next: > * mprotect case 5 shifting the boundary up. > */ > - adjust_next = (end - next->vm_start) >> PAGE_SHIFT; > + adjust_next = (end - next->vm_start); > exporter = next; > importer = vma; > VM_WARN_ON(expand != importer); > @@ -768,7 +768,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, > * split_vma inserting another: so it must be > * mprotect case 4 shifting the boundary down. > */ > - adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); > + adjust_next = -(vma->vm_end - end); > exporter = vma; > importer = next; > VM_WARN_ON(expand != importer); > @@ -840,8 +840,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, > } > vma->vm_pgoff = pgoff; > if (adjust_next) { > - next->vm_start += adjust_next << PAGE_SHIFT; > - next->vm_pgoff += adjust_next; > + next->vm_start += adjust_next; > + next->vm_pgoff += adjust_next >> PAGE_SHIFT; > } > > if (root) { >
On Tue, Sep 08, 2020 at 05:31:22PM +0200, Vlastimil Babka wrote: >On 8/28/20 10:10 AM, Wei Yang wrote: >> Instead of convert adjust_next between virtual address and page frame >> number, let's just store the virtual address into adjust_next. > >IMHO more precisely/less confusing it's "bytes" and "pages" instead of "virtual >address" (which is absolute address, but this variable holds a difference) and >"page frame number" (which is related to absolute physical address, but what we >have is difference in pages in virtual address space). > Thanks for your comment. To be honest, I am not sure which one is more precise. English is not my mother tongue. If others think this is better, I am fine to adjust this. >> Also, this patch fixes one typo in the comment of >> vma_adjust_trans_huge(). >> >> Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com> > >Other than that, seems like it leads to less shifting, so >Acked-by: Vlastimil Babka <vbabka@suse.cz> > >> --- >> mm/huge_memory.c | 4 ++-- >> mm/mmap.c | 8 ++++---- >> 2 files changed, 6 insertions(+), 6 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 78c84bee7e29..2c633ba14440 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -2300,13 +2300,13 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma, >> >> /* >> * If we're also updating the vma->vm_next->vm_start, if the new >> - * vm_next->vm_start isn't page aligned and it could previously >> + * vm_next->vm_start isn't hpage aligned and it could previously >> * contain an hugepage: check if we need to split an huge pmd. >> */ >> if (adjust_next > 0) { >> struct vm_area_struct *next = vma->vm_next; >> unsigned long nstart = next->vm_start; >> - nstart += adjust_next << PAGE_SHIFT; >> + nstart += adjust_next; >> if (nstart & ~HPAGE_PMD_MASK && >> (nstart & HPAGE_PMD_MASK) >= next->vm_start && >> (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) >> diff --git a/mm/mmap.c b/mm/mmap.c >> index 90b1298d4222..e4c9bbfd4103 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -758,7 +758,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, >> * vma expands, overlapping part of the next: >> * mprotect case 5 shifting the boundary up. >> */ >> - adjust_next = (end - next->vm_start) >> PAGE_SHIFT; >> + adjust_next = (end - next->vm_start); >> exporter = next; >> importer = vma; >> VM_WARN_ON(expand != importer); >> @@ -768,7 +768,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, >> * split_vma inserting another: so it must be >> * mprotect case 4 shifting the boundary down. >> */ >> - adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); >> + adjust_next = -(vma->vm_end - end); >> exporter = vma; >> importer = next; >> VM_WARN_ON(expand != importer); >> @@ -840,8 +840,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, >> } >> vma->vm_pgoff = pgoff; >> if (adjust_next) { >> - next->vm_start += adjust_next << PAGE_SHIFT; >> - next->vm_pgoff += adjust_next; >> + next->vm_start += adjust_next; >> + next->vm_pgoff += adjust_next >> PAGE_SHIFT; >> } >> >> if (root) { >>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 78c84bee7e29..2c633ba14440 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2300,13 +2300,13 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma, /* * If we're also updating the vma->vm_next->vm_start, if the new - * vm_next->vm_start isn't page aligned and it could previously + * vm_next->vm_start isn't hpage aligned and it could previously * contain an hugepage: check if we need to split an huge pmd. */ if (adjust_next > 0) { struct vm_area_struct *next = vma->vm_next; unsigned long nstart = next->vm_start; - nstart += adjust_next << PAGE_SHIFT; + nstart += adjust_next; if (nstart & ~HPAGE_PMD_MASK && (nstart & HPAGE_PMD_MASK) >= next->vm_start && (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) diff --git a/mm/mmap.c b/mm/mmap.c index 90b1298d4222..e4c9bbfd4103 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -758,7 +758,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, * vma expands, overlapping part of the next: * mprotect case 5 shifting the boundary up. */ - adjust_next = (end - next->vm_start) >> PAGE_SHIFT; + adjust_next = (end - next->vm_start); exporter = next; importer = vma; VM_WARN_ON(expand != importer); @@ -768,7 +768,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, * split_vma inserting another: so it must be * mprotect case 4 shifting the boundary down. */ - adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); + adjust_next = -(vma->vm_end - end); exporter = vma; importer = next; VM_WARN_ON(expand != importer); @@ -840,8 +840,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, } vma->vm_pgoff = pgoff; if (adjust_next) { - next->vm_start += adjust_next << PAGE_SHIFT; - next->vm_pgoff += adjust_next; + next->vm_start += adjust_next; + next->vm_pgoff += adjust_next >> PAGE_SHIFT; } if (root) {
Instead of convert adjust_next between virtual address and page frame number, let's just store the virtual address into adjust_next. Also, this patch fixes one typo in the comment of vma_adjust_trans_huge(). Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com> --- mm/huge_memory.c | 4 ++-- mm/mmap.c | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-)