If memory charge failed, instead of returning the hpage but with an error,
allow the function to cleanup the folio properly, which is normally what a
function should do in this case - either return successfully, or return
with no side effect of partial runs with an indicated error.
This will also avoid the caller calling mem_cgroup_uncharge() unnecessarily
with either anon or shmem path (even if it's safe to do so).
Cc: Yang Shi <[email protected]>
Reviewed-by: David Stevens <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Signed-off-by: Peter Xu <[email protected]>
---
v1->v2:
- Enhance commit message, drop "Fixes:" and "Cc: stable" tag, add R-bs.
---
mm/khugepaged.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 8dbc39896811..941d1c7ea910 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1063,12 +1063,19 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
GFP_TRANSHUGE);
int node = hpage_collapse_find_target_node(cc);
+ struct folio *folio;
if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
return SCAN_ALLOC_HUGE_PAGE_FAIL;
- if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
+
+ folio = page_folio(*hpage);
+ if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
+ folio_put(folio);
+ *hpage = NULL;
return SCAN_CGROUP_CHARGE_FAIL;
+ }
count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
+
return SCAN_SUCCEED;
}
--
2.39.1
On Wed, Feb 22, 2023 at 11:52 AM Peter Xu <[email protected]> wrote:
>
> If memory charge failed, instead of returning the hpage but with an error,
> allow the function to cleanup the folio properly, which is normally what a
> function should do in this case - either return successfully, or return
> with no side effect of partial runs with an indicated error.
>
> This will also avoid the caller calling mem_cgroup_uncharge() unnecessarily
> with either anon or shmem path (even if it's safe to do so).
Thanks for the cleanup. Reviewed-by: Yang Shi <[email protected]>
>
> Cc: Yang Shi <[email protected]>
> Reviewed-by: David Stevens <[email protected]>
> Acked-by: Johannes Weiner <[email protected]>
> Signed-off-by: Peter Xu <[email protected]>
> ---
> v1->v2:
> - Enhance commit message, drop "Fixes:" and "Cc: stable" tag, add R-bs.
> ---
> mm/khugepaged.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 8dbc39896811..941d1c7ea910 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1063,12 +1063,19 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
> gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
> GFP_TRANSHUGE);
> int node = hpage_collapse_find_target_node(cc);
> + struct folio *folio;
>
> if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
> return SCAN_ALLOC_HUGE_PAGE_FAIL;
> - if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
> +
> + folio = page_folio(*hpage);
> + if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
> + folio_put(folio);
> + *hpage = NULL;
> return SCAN_CGROUP_CHARGE_FAIL;
> + }
> count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
> +
> return SCAN_SUCCEED;
> }
>
> --
> 2.39.1
>
On Feb 22 14:53, Yang Shi wrote:
> On Wed, Feb 22, 2023 at 11:52 AM Peter Xu <[email protected]> wrote:
> >
> > If memory charge failed, instead of returning the hpage but with an error,
> > allow the function to cleanup the folio properly, which is normally what a
> > function should do in this case - either return successfully, or return
> > with no side effect of partial runs with an indicated error.
> >
> > This will also avoid the caller calling mem_cgroup_uncharge() unnecessarily
> > with either anon or shmem path (even if it's safe to do so).
>
> Thanks for the cleanup. Reviewed-by: Yang Shi <[email protected]>
>
> >
> > Cc: Yang Shi <[email protected]>
> > Reviewed-by: David Stevens <[email protected]>
> > Acked-by: Johannes Weiner <[email protected]>
> > Signed-off-by: Peter Xu <[email protected]>
> > ---
> > v1->v2:
> > - Enhance commit message, drop "Fixes:" and "Cc: stable" tag, add R-bs.
> > ---
> > mm/khugepaged.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 8dbc39896811..941d1c7ea910 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -1063,12 +1063,19 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
> > gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
> > GFP_TRANSHUGE);
> > int node = hpage_collapse_find_target_node(cc);
> > + struct folio *folio;
> >
> > if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
> > return SCAN_ALLOC_HUGE_PAGE_FAIL;
> > - if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
> > +
> > + folio = page_folio(*hpage);
> > + if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
> > + folio_put(folio);
> > + *hpage = NULL;
> > return SCAN_CGROUP_CHARGE_FAIL;
> > + }
> > count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
> > +
> > return SCAN_SUCCEED;
> > }
> >
> > --
> > 2.39.1
> >
>
Thanks, Peter.
Can we also get rid of the unnecessary mem_cgroup_uncharge() calls while we're
at it? Maybe this deserves a separate patch, but after Yang's cleanup of the
!NUMA case (where we would preallocate a hugepage) we can depend on put_page()
do take care of that for us.
Regardless, can have my
Reviewed-by: Zach O'Keefe <[email protected]>
On Thu, Mar 02, 2023 at 03:21:50PM -0800, Zach O'Keefe wrote:
> On Feb 22 14:53, Yang Shi wrote:
> > On Wed, Feb 22, 2023 at 11:52 AM Peter Xu <[email protected]> wrote:
> > >
> > > If memory charge failed, instead of returning the hpage but with an error,
> > > allow the function to cleanup the folio properly, which is normally what a
> > > function should do in this case - either return successfully, or return
> > > with no side effect of partial runs with an indicated error.
> > >
> > > This will also avoid the caller calling mem_cgroup_uncharge() unnecessarily
> > > with either anon or shmem path (even if it's safe to do so).
> >
> > Thanks for the cleanup. Reviewed-by: Yang Shi <[email protected]>
> >
> > >
> > > Cc: Yang Shi <[email protected]>
> > > Reviewed-by: David Stevens <[email protected]>
> > > Acked-by: Johannes Weiner <[email protected]>
> > > Signed-off-by: Peter Xu <[email protected]>
> > > ---
> > > v1->v2:
> > > - Enhance commit message, drop "Fixes:" and "Cc: stable" tag, add R-bs.
> > > ---
> > > mm/khugepaged.c | 9 ++++++++-
> > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > > index 8dbc39896811..941d1c7ea910 100644
> > > --- a/mm/khugepaged.c
> > > +++ b/mm/khugepaged.c
> > > @@ -1063,12 +1063,19 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
> > > gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
> > > GFP_TRANSHUGE);
> > > int node = hpage_collapse_find_target_node(cc);
> > > + struct folio *folio;
> > >
> > > if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
> > > return SCAN_ALLOC_HUGE_PAGE_FAIL;
> > > - if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
> > > +
> > > + folio = page_folio(*hpage);
> > > + if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
> > > + folio_put(folio);
> > > + *hpage = NULL;
> > > return SCAN_CGROUP_CHARGE_FAIL;
> > > + }
> > > count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
> > > +
> > > return SCAN_SUCCEED;
> > > }
> > >
> > > --
> > > 2.39.1
> > >
> >
>
> Thanks, Peter.
>
> Can we also get rid of the unnecessary mem_cgroup_uncharge() calls while we're
> at it? Maybe this deserves a separate patch, but after Yang's cleanup of the
> !NUMA case (where we would preallocate a hugepage) we can depend on put_page()
> do take care of that for us.
Makes sense to me. I can prepare a separate patch to clean it up.
>
> Regardless, can have my
>
> Reviewed-by: Zach O'Keefe <[email protected]>
Thanks!
--
Peter Xu