| Message ID | 20201125034655.27687-1-willy@infradead.org |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [1/2] sparc: Fix handling of page table constructor failure | expand |
On 25.11.20 04:46, Matthew Wilcox (Oracle) wrote: > The page has just been allocated, so its refcount is 1. free_unref_page() > is for use on pages which have a zero refcount. Use __free_page() > like the other implementations of pte_alloc_one(). > > Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > arch/sparc/mm/init_64.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c > index 96edf64d4fb3..182bb7bdaa0a 100644 > --- a/arch/sparc/mm/init_64.c > +++ b/arch/sparc/mm/init_64.c > @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) > if (!page) > return NULL; > if (!pgtable_pte_page_ctor(page)) { > - free_unref_page(page); > + __free_page(page); > return NULL; > } > return (pte_t *) page_address(page); > I wonder if reusing __pte_alloc_one() - e.g., internally - would be even cleaner. Reviewed-by: David Hildenbrand <david@redhat.com>
On Wed, Nov 25, 2020 at 03:46:54AM +0000, Matthew Wilcox (Oracle) wrote: > The page has just been allocated, so its refcount is 1. free_unref_page() > is for use on pages which have a zero refcount. Use __free_page() > like the other implementations of pte_alloc_one(). > > Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> > --- > arch/sparc/mm/init_64.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c > index 96edf64d4fb3..182bb7bdaa0a 100644 > --- a/arch/sparc/mm/init_64.c > +++ b/arch/sparc/mm/init_64.c > @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) > if (!page) > return NULL; > if (!pgtable_pte_page_ctor(page)) { > - free_unref_page(page); > + __free_page(page); > return NULL; > } > return (pte_t *) page_address(page); > -- > 2.29.2 >
On Wed, Nov 25, 2020 at 09:43:15AM +0100, David Hildenbrand wrote: > On 25.11.20 04:46, Matthew Wilcox (Oracle) wrote: > > The page has just been allocated, so its refcount is 1. free_unref_page() > > is for use on pages which have a zero refcount. Use __free_page() > > like the other implementations of pte_alloc_one(). > > > > Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > --- > > arch/sparc/mm/init_64.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c > > index 96edf64d4fb3..182bb7bdaa0a 100644 > > --- a/arch/sparc/mm/init_64.c > > +++ b/arch/sparc/mm/init_64.c > > @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) > > if (!page) > > return NULL; > > if (!pgtable_pte_page_ctor(page)) { > > - free_unref_page(page); > > + __free_page(page); > > return NULL; > > } > > return (pte_t *) page_address(page); > > > > I wonder if reusing __pte_alloc_one() - e.g., internally - would be even > cleaner. It's really awkward to do because pgtable_t is defined differently. The clean thing to do would be: --- arch/sparc/include/asm/page_64.h -typedef pte_t *pgtable_t; +typedef struct page *pgtable_t; and then do all the other changes that would require. But that feels like a lot more work than appropriate to fix this unlikely bug.
On 11/25/20 4:46 AM, Matthew Wilcox (Oracle) wrote: > The page has just been allocated, so its refcount is 1. free_unref_page() > is for use on pages which have a zero refcount. Use __free_page() > like the other implementations of pte_alloc_one(). > > Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > arch/sparc/mm/init_64.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c > index 96edf64d4fb3..182bb7bdaa0a 100644 > --- a/arch/sparc/mm/init_64.c > +++ b/arch/sparc/mm/init_64.c > @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) > if (!page) > return NULL; > if (!pgtable_pte_page_ctor(page)) { > - free_unref_page(page); > + __free_page(page); > return NULL; > } > return (pte_t *) page_address(page); >
On 25.11.20 13:10, Matthew Wilcox wrote: > On Wed, Nov 25, 2020 at 09:43:15AM +0100, David Hildenbrand wrote: >> On 25.11.20 04:46, Matthew Wilcox (Oracle) wrote: >>> The page has just been allocated, so its refcount is 1. free_unref_page() >>> is for use on pages which have a zero refcount. Use __free_page() >>> like the other implementations of pte_alloc_one(). >>> >>> Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") >>> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> >>> --- >>> arch/sparc/mm/init_64.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c >>> index 96edf64d4fb3..182bb7bdaa0a 100644 >>> --- a/arch/sparc/mm/init_64.c >>> +++ b/arch/sparc/mm/init_64.c >>> @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) >>> if (!page) >>> return NULL; >>> if (!pgtable_pte_page_ctor(page)) { >>> - free_unref_page(page); >>> + __free_page(page); >>> return NULL; >>> } >>> return (pte_t *) page_address(page); >>> >> >> I wonder if reusing __pte_alloc_one() - e.g., internally - would be even >> cleaner. > > It's really awkward to do because pgtable_t is defined differently. > The clean thing to do would be: > > --- arch/sparc/include/asm/page_64.h > -typedef pte_t *pgtable_t; > +typedef struct page *pgtable_t; > > and then do all the other changes that would require. > > But that feels like a lot more work than appropriate to fix this > unlikely bug. Yeah, cleanups would have to come on top of the fix of course. But I can understand that you have plenty of better things to do :) ... maybe sparc people want to work on that at one point.
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index 96edf64d4fb3..182bb7bdaa0a 100644 --- a/arch/sparc/mm/init_64.c +++ b/arch/sparc/mm/init_64.c @@ -2894,7 +2894,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) if (!page) return NULL; if (!pgtable_pte_page_ctor(page)) { - free_unref_page(page); + __free_page(page); return NULL; } return (pte_t *) page_address(page);
The page has just been allocated, so its refcount is 1. free_unref_page() is for use on pages which have a zero refcount. Use __free_page() like the other implementations of pte_alloc_one(). Fixes: 1ae9ae5f7df7 ("sparc: handle pgtable_page_ctor() fail") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- arch/sparc/mm/init_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)