| Message ID | 20240513074712.7608-4-ioworker0@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Reclaim lazyfree THP without splitting | expand |
On 2024/5/13 15:47, Lance Yang wrote: > The TTU_SPLIT_HUGE_PMD will no longer perform immediately, so we might > encounter a PMD-mapped THP missing the mlock in the VM_LOCKED range > during the pagewalk. It's likely necessary to mlock this THP to prevent > it from being picked up during page reclaim. > > Suggested-by: Baolin Wang <baolin.wang@linux.alibaba.com> > Signed-off-by: Lance Yang <ioworker0@gmail.com> IMO, this patch should be merged into patch 2, otherwise patch 2 is buggy. Quote the description in the 'submission patches.rst' document: "When dividing your change into a series of patches, take special care to ensure that the kernel builds and runs properly after each patch in the series. Developers using ``git bisect`` to track down a problem can end up splitting your patch series at any point; they will not thank you if you introduce bugs in the middle." > --- > mm/rmap.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 4c4d14325f2e..08a93347f283 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1671,7 +1671,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > if (!(flags & TTU_IGNORE_MLOCK) && > (vma->vm_flags & VM_LOCKED)) { > /* Restore the mlock which got missed */ > - if (!folio_test_large(folio)) > + if (!folio_test_large(folio) || > + (!pvmw.pte && (flags & TTU_SPLIT_HUGE_PMD))) > mlock_vma_folio(folio, vma); > goto walk_done_err; > }
On Tue, May 14, 2024 at 2:41 PM Baolin Wang <baolin.wang@linux.alibaba.com> wrote: > > > > On 2024/5/13 15:47, Lance Yang wrote: > > The TTU_SPLIT_HUGE_PMD will no longer perform immediately, so we might > > encounter a PMD-mapped THP missing the mlock in the VM_LOCKED range > > during the pagewalk. It's likely necessary to mlock this THP to prevent > > it from being picked up during page reclaim. > > > > Suggested-by: Baolin Wang <baolin.wang@linux.alibaba.com> > > Signed-off-by: Lance Yang <ioworker0@gmail.com> > > IMO, this patch should be merged into patch 2, otherwise patch 2 is > buggy. Quote the description in the 'submission patches.rst' document: > > "When dividing your change into a series of patches, take special care > to ensure that the kernel builds and runs properly after each patch in > the series. Developers using ``git bisect`` to track down a problem can > end up splitting your patch series at any point; they will not thank you > if you introduce bugs in the middle." Thanks for bringing this up! I completely agree that this patch should be merged into patch2. Thanks, Lance > > > --- > > mm/rmap.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/mm/rmap.c b/mm/rmap.c > > index 4c4d14325f2e..08a93347f283 100644 > > --- a/mm/rmap.c > > +++ b/mm/rmap.c > > @@ -1671,7 +1671,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > > if (!(flags & TTU_IGNORE_MLOCK) && > > (vma->vm_flags & VM_LOCKED)) { > > /* Restore the mlock which got missed */ > > - if (!folio_test_large(folio)) > > + if (!folio_test_large(folio) || > > + (!pvmw.pte && (flags & TTU_SPLIT_HUGE_PMD))) > > mlock_vma_folio(folio, vma); > > goto walk_done_err; > > }
diff --git a/mm/rmap.c b/mm/rmap.c index 4c4d14325f2e..08a93347f283 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1671,7 +1671,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, if (!(flags & TTU_IGNORE_MLOCK) && (vma->vm_flags & VM_LOCKED)) { /* Restore the mlock which got missed */ - if (!folio_test_large(folio)) + if (!folio_test_large(folio) || + (!pvmw.pte && (flags & TTU_SPLIT_HUGE_PMD))) mlock_vma_folio(folio, vma); goto walk_done_err; }
The TTU_SPLIT_HUGE_PMD will no longer perform immediately, so we might encounter a PMD-mapped THP missing the mlock in the VM_LOCKED range during the pagewalk. It's likely necessary to mlock this THP to prevent it from being picked up during page reclaim. Suggested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Signed-off-by: Lance Yang <ioworker0@gmail.com> --- mm/rmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)