| Message ID | 1408635812-31584-6-git-send-email-steve.capper@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Aug 21, 2014 at 04:43:31PM +0100, Steve Capper wrote: > In order to implement fast_get_user_pages we need to ensure that the > page table walker is protected from page table pages being freed from > under it. > > This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging > to address spaces with multiple users will be call_rcu_sched freed. > Meaning that disabling interrupts will block the free and protect the > fast gup page walker. > > Signed-off-by: Steve Capper <steve.capper@linaro.org> I'm happy to take this patch independently of this series. But if the whole series goes in via some other tree (mm): Acked-by: Catalin Marinas <catalin.marinas@arm.com>
On Wed, Aug 27, 2014 at 11:48:41AM +0100, Catalin Marinas wrote: > On Thu, Aug 21, 2014 at 04:43:31PM +0100, Steve Capper wrote: > > In order to implement fast_get_user_pages we need to ensure that the > > page table walker is protected from page table pages being freed from > > under it. > > > > This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging > > to address spaces with multiple users will be call_rcu_sched freed. > > Meaning that disabling interrupts will block the free and protect the > > fast gup page walker. > > > > Signed-off-by: Steve Capper <steve.capper@linaro.org> > > I'm happy to take this patch independently of this series. But if the > whole series goes in via some other tree (mm): > > Acked-by: Catalin Marinas <catalin.marinas@arm.com> Thanks. If patch #1 looks okay to the mm folks, I'm hoping this patch can be merged via the same tree.
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index fd4e81a..ce9062b 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -54,6 +54,7 @@ config ARM64 select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_RCU_TABLE_FREE select HAVE_SYSCALL_TRACEPOINTS select IRQ_DOMAIN select MODULES_USE_ELF_RELA diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h index 62731ef..a82c0c5 100644 --- a/arch/arm64/include/asm/tlb.h +++ b/arch/arm64/include/asm/tlb.h @@ -23,6 +23,20 @@ #include <asm-generic/tlb.h> +#include <linux/pagemap.h> +#include <linux/swap.h> + +#ifdef CONFIG_HAVE_RCU_TABLE_FREE + +#define tlb_remove_entry(tlb, entry) tlb_remove_table(tlb, entry) +static inline void __tlb_remove_table(void *_table) +{ + free_page_and_swap_cache((struct page *)_table); +} +#else +#define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry) +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */ + /* * There's three ways the TLB shootdown code is used: * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region(). @@ -88,7 +102,7 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, { pgtable_page_dtor(pte); tlb_add_flush(tlb, addr); - tlb_remove_page(tlb, pte); + tlb_remove_entry(tlb, pte); } #if CONFIG_ARM64_PGTABLE_LEVELS > 2 @@ -96,7 +110,7 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr) { tlb_add_flush(tlb, addr); - tlb_remove_page(tlb, virt_to_page(pmdp)); + tlb_remove_entry(tlb, virt_to_page(pmdp)); } #endif @@ -105,7 +119,7 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp, unsigned long addr) { tlb_add_flush(tlb, addr); - tlb_remove_page(tlb, virt_to_page(pudp)); + tlb_remove_entry(tlb, virt_to_page(pudp)); } #endif
In order to implement fast_get_user_pages we need to ensure that the page table walker is protected from page table pages being freed from under it. This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging to address spaces with multiple users will be call_rcu_sched freed. Meaning that disabling interrupts will block the free and protect the fast gup page walker. Signed-off-by: Steve Capper <steve.capper@linaro.org> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/tlb.h | 20 +++++++++++++++++--- 2 files changed, 18 insertions(+), 3 deletions(-)