| Message ID | 20220126060514.1574935-4-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | page table check fixes and cleanups | expand |
On Wed, 26 Jan 2022, Pasha Tatashin wrote: > Unify the code that flushes, clears pmd entry, and frees the PTE table > level into a new function collapse_and_free_pmd(). > > This clean-up is useful as in the next patch we will add another call to > this function to iterate through PTE prior to freeing the level for page > table check. > > Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: David Rientjes <rientjes@google.com> One nit below. > --- > mm/khugepaged.c | 32 ++++++++++++++++---------------- > 1 file changed, 16 insertions(+), 16 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 35f14d0a00a6..440112355ffe 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1416,6 +1416,17 @@ static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, > return 0; > } > > +static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma, > + unsigned long addr, pmd_t *pmdp) > +{ > + spinlock_t *ptl = pmd_lock(vma->vm_mm, pmdp); > + pmd_t pmd = pmdp_collapse_flush(vma, addr, pmdp); > + > + spin_unlock(ptl); No strong objection, but I think the typical style would be to declare the local variables separately and avoid mixing the code, especially in cases when taking locks (and not just initializing the local variables). > + mm_dec_nr_ptes(mm); > + pte_free(mm, pmd_pgtable(pmd)); > +} > + > /** > * collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at > * address haddr. > @@ -1433,7 +1444,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) > struct vm_area_struct *vma = find_vma(mm, haddr); > struct page *hpage; > pte_t *start_pte, *pte; > - pmd_t *pmd, _pmd; > + pmd_t *pmd; > spinlock_t *ptl; > int count = 0; > int i; > @@ -1509,12 +1520,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) > } > > /* step 4: collapse pmd */ > - ptl = pmd_lock(vma->vm_mm, pmd); > - _pmd = pmdp_collapse_flush(vma, haddr, pmd); > - spin_unlock(ptl); > - mm_dec_nr_ptes(mm); > - pte_free(mm, pmd_pgtable(_pmd)); > - > + collapse_and_free_pmd(mm, vma, haddr, pmd); > drop_hpage: > unlock_page(hpage); > put_page(hpage); > @@ -1552,7 +1558,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) > struct vm_area_struct *vma; > struct mm_struct *mm; > unsigned long addr; > - pmd_t *pmd, _pmd; > + pmd_t *pmd; > > i_mmap_lock_write(mapping); > vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { > @@ -1591,14 +1597,8 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) > * reverse order. Trylock is a way to avoid deadlock. > */ > if (mmap_write_trylock(mm)) { > - if (!khugepaged_test_exit(mm)) { > - spinlock_t *ptl = pmd_lock(mm, pmd); > - /* assume page table is clear */ > - _pmd = pmdp_collapse_flush(vma, addr, pmd); > - spin_unlock(ptl); > - mm_dec_nr_ptes(mm); > - pte_free(mm, pmd_pgtable(_pmd)); > - } > + if (!khugepaged_test_exit(mm)) > + collapse_and_free_pmd(mm, vma, addr, pmd); > mmap_write_unlock(mm); > } else { > /* Try again later */ > -- > 2.35.0.rc0.227.g00780c9af4-goog > >
On Wed, Jan 26, 2022 at 1:34 AM David Rientjes <rientjes@google.com> wrote: > > On Wed, 26 Jan 2022, Pasha Tatashin wrote: > > > Unify the code that flushes, clears pmd entry, and frees the PTE table > > level into a new function collapse_and_free_pmd(). > > > > This clean-up is useful as in the next patch we will add another call to > > this function to iterate through PTE prior to freeing the level for page > > table check. > > > > Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> > > Acked-by: David Rientjes <rientjes@google.com> Thank you, David. > > One nit below. > > > --- > > mm/khugepaged.c | 32 ++++++++++++++++---------------- > > 1 file changed, 16 insertions(+), 16 deletions(-) > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > index 35f14d0a00a6..440112355ffe 100644 > > --- a/mm/khugepaged.c > > +++ b/mm/khugepaged.c > > @@ -1416,6 +1416,17 @@ static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, > > return 0; > > } > > > > +static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma, > > + unsigned long addr, pmd_t *pmdp) > > +{ > > + spinlock_t *ptl = pmd_lock(vma->vm_mm, pmdp); > > + pmd_t pmd = pmdp_collapse_flush(vma, addr, pmdp); > > + > > + spin_unlock(ptl); > > No strong objection, but I think the typical style would be to declare the > local variables separately and avoid mixing the code, especially in cases > when taking locks (and not just initializing the local variables). I will address this in the next revision. Thank you, Pasha
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 35f14d0a00a6..440112355ffe 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1416,6 +1416,17 @@ static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm, return 0; } +static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp) +{ + spinlock_t *ptl = pmd_lock(vma->vm_mm, pmdp); + pmd_t pmd = pmdp_collapse_flush(vma, addr, pmdp); + + spin_unlock(ptl); + mm_dec_nr_ptes(mm); + pte_free(mm, pmd_pgtable(pmd)); +} + /** * collapse_pte_mapped_thp - Try to collapse a pte-mapped THP for mm at * address haddr. @@ -1433,7 +1444,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) struct vm_area_struct *vma = find_vma(mm, haddr); struct page *hpage; pte_t *start_pte, *pte; - pmd_t *pmd, _pmd; + pmd_t *pmd; spinlock_t *ptl; int count = 0; int i; @@ -1509,12 +1520,7 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) } /* step 4: collapse pmd */ - ptl = pmd_lock(vma->vm_mm, pmd); - _pmd = pmdp_collapse_flush(vma, haddr, pmd); - spin_unlock(ptl); - mm_dec_nr_ptes(mm); - pte_free(mm, pmd_pgtable(_pmd)); - + collapse_and_free_pmd(mm, vma, haddr, pmd); drop_hpage: unlock_page(hpage); put_page(hpage); @@ -1552,7 +1558,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) struct vm_area_struct *vma; struct mm_struct *mm; unsigned long addr; - pmd_t *pmd, _pmd; + pmd_t *pmd; i_mmap_lock_write(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { @@ -1591,14 +1597,8 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) * reverse order. Trylock is a way to avoid deadlock. */ if (mmap_write_trylock(mm)) { - if (!khugepaged_test_exit(mm)) { - spinlock_t *ptl = pmd_lock(mm, pmd); - /* assume page table is clear */ - _pmd = pmdp_collapse_flush(vma, addr, pmd); - spin_unlock(ptl); - mm_dec_nr_ptes(mm); - pte_free(mm, pmd_pgtable(_pmd)); - } + if (!khugepaged_test_exit(mm)) + collapse_and_free_pmd(mm, vma, addr, pmd); mmap_write_unlock(mm); } else { /* Try again later */
Unify the code that flushes, clears pmd entry, and frees the PTE table level into a new function collapse_and_free_pmd(). This clean-up is useful as in the next patch we will add another call to this function to iterate through PTE prior to freeing the level for page table check. Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> --- mm/khugepaged.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-)