* [PATCH] hugetlb: fix race condition in hugetlb_fault() @ 2012-03-30 20:07 Chris Metcalf 2012-03-31 12:27 ` Hillf Danton 0 siblings, 1 reply; 17+ messages in thread From: Chris Metcalf @ 2012-03-30 20:07 UTC (permalink / raw) To: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, Hillf Danton, KAMEZAWA Hiroyuki, Hugh Dickins The race is as follows. Suppose a multi-threaded task forks a new process, thus bumping up the ref count on all the pages. While the fork is occurring (and thus we have marked all the PTEs as read-only), another thread in the original process tries to write to a huge page, taking an access violation from the write-protect and calling hugetlb_cow(). Now, suppose the fork() fails. It will undo the COW and decrement the ref count on the pages, so the ref count on the huge page drops back to 1. Meanwhile hugetlb_cow() also decrements the ref count by one on the original page, since the original address space doesn't need it any more, having copied a new page to replace the original page. This leaves the ref count at zero, and when we call unlock_page(), we panic. The solution is to take an extra reference to the page while we are holding the lock on it. Cc: stable@kernel.org Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> --- mm/hugetlb.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4531be2..ab674fc 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2703,8 +2703,10 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, * so no worry about deadlock. */ page = pte_page(entry); - if (page != pagecache_page) + if (page != pagecache_page) { + get_page(page); lock_page(page); + } spin_lock(&mm->page_table_lock); /* Check for a racing update before calling hugetlb_cow */ @@ -2732,8 +2734,10 @@ out_page_table_lock: unlock_page(pagecache_page); put_page(pagecache_page); } - if (page != pagecache_page) + if (page != pagecache_page) { unlock_page(page); + put_page(page); + } out_mutex: mutex_unlock(&hugetlb_instantiation_mutex); -- 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH] hugetlb: fix race condition in hugetlb_fault() 2012-03-30 20:07 [PATCH] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf @ 2012-03-31 12:27 ` Hillf Danton 2012-03-30 19:37 ` [PATCH v2] arch/tile: support multiple huge page sizes dynamically Chris Metcalf 2012-03-30 20:07 ` [PATCH v2] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf 0 siblings, 2 replies; 17+ messages in thread From: Hillf Danton @ 2012-03-31 12:27 UTC (permalink / raw) To: Chris Metcalf Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Sat, Mar 31, 2012 at 4:07 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: > The race is as follows. Suppose a multi-threaded task forks a new > process, thus bumping up the ref count on all the pages. While the fork > is occurring (and thus we have marked all the PTEs as read-only), another > thread in the original process tries to write to a huge page, taking an > access violation from the write-protect and calling hugetlb_cow(). Now, > suppose the fork() fails. It will undo the COW and decrement the ref > count on the pages, so the ref count on the huge page drops back to 1. > Meanwhile hugetlb_cow() also decrements the ref count by one on the > original page, since the original address space doesn't need it any more, > having copied a new page to replace the original page. This leaves the > ref count at zero, and when we call unlock_page(), we panic. > > The solution is to take an extra reference to the page while we are > holding the lock on it. > > Cc: stable@kernel.org > Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> > --- > mm/hugetlb.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 4531be2..ab674fc 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2703,8 +2703,10 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, > * so no worry about deadlock. > */ > page = pte_page(entry); > - if (page != pagecache_page) > + if (page != pagecache_page) { > + get_page(page); > lock_page(page); > + } > Perhaps, directly get page? page = pte_page(entry); + get_page(page); if (page != pagecache_page) lock_page(page); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2] arch/tile: support multiple huge page sizes dynamically 2012-03-31 12:27 ` Hillf Danton @ 2012-03-30 19:37 ` Chris Metcalf 2012-03-31 14:03 ` Hillf Danton 2012-03-30 20:07 ` [PATCH v2] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf 1 sibling, 1 reply; 17+ messages in thread From: Chris Metcalf @ 2012-03-30 19:37 UTC (permalink / raw) To: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins, Hillf Danton This change adds support for a new "super" bit in the PTE, and a new arch_make_huge_pte() method called from make_huge_pte(). The Tilera hypervisor sees the bit set at a given level of the page table and gangs together 4, 16, or 64 consecutive pages from that level of the hierarchy to create a larger TLB entry. One extra "super" page size can be specified at each of the three levels of the page table hierarchy on tilegx, using the "hugepagesz" argument on the boot command line. A new hypervisor API is added to allow Linux to tell the hypervisor how many PTEs to gang together at each level of the page table. To allow pre-allocating huge pages larger than the buddy allocator can handle, this change modifies the Tilera bootmem support to put all of memory on tilegx platforms into bootmem. As part of this change I eliminate the vestigial CONFIG_HIGHPTE support, which never worked anyway, and eliminate the hv_page_size() API in favor of the standard vma_kernel_pagesize() API. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> --- This change incorporates Hillf Danton's suggestion to not use a macro for arch_make_huge_pte() but instead use the standard hugetlb model of providing an empty inline function for every other platform. arch/ia64/include/asm/hugetlb.h | 6 + arch/mips/include/asm/hugetlb.h | 6 + arch/powerpc/include/asm/hugetlb.h | 6 + arch/s390/include/asm/hugetlb.h | 6 + arch/sh/include/asm/hugetlb.h | 6 + arch/sparc/include/asm/hugetlb.h | 6 + arch/tile/Kconfig | 8 ++ arch/tile/include/asm/hugetlb.h | 22 ++++ arch/tile/include/asm/page.h | 5 +- arch/tile/include/asm/pgtable.h | 12 +- arch/tile/include/asm/tlbflush.h | 17 +-- arch/tile/include/hv/hypervisor.h | 70 ++++++++++- arch/tile/kernel/hvglue.lds | 3 +- arch/tile/kernel/proc.c | 1 + arch/tile/kernel/setup.c | 152 +++++++++++++++-------- arch/tile/kernel/tlb.c | 11 +- arch/tile/mm/fault.c | 2 +- arch/tile/mm/homecache.c | 1 + arch/tile/mm/hugetlbpage.c | 241 ++++++++++++++++++++++++++---------- arch/tile/mm/init.c | 4 + arch/tile/mm/pgtable.c | 13 -- arch/x86/include/asm/hugetlb.h | 6 + mm/hugetlb.c | 1 + 23 files changed, 449 insertions(+), 156 deletions(-) diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h index da55c63..47d8b51 100644 --- a/arch/ia64/include/asm/hugetlb.h +++ b/arch/ia64/include/asm/hugetlb.h @@ -77,4 +77,10 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_IA64_HUGETLB_H */ diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h index 58d3688..f5f54f3 100644 --- a/arch/mips/include/asm/hugetlb.h +++ b/arch/mips/include/asm/hugetlb.h @@ -112,4 +112,10 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* __ASM_HUGETLB_H */ diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h index dfdb95b..8677332 100644 --- a/arch/powerpc/include/asm/hugetlb.h +++ b/arch/powerpc/include/asm/hugetlb.h @@ -172,4 +172,10 @@ static inline void reserve_hugetlb_gpages(void) } #endif +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_POWERPC_HUGETLB_H */ diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h index 799ed0f..3f2cbcc 100644 --- a/arch/s390/include/asm/hugetlb.h +++ b/arch/s390/include/asm/hugetlb.h @@ -146,4 +146,10 @@ static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, huge_ptep_invalidate(vma->vm_mm, address, ptep); } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_S390_HUGETLB_H */ diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h index 967068f..0e0659c 100644 --- a/arch/sh/include/asm/hugetlb.h +++ b/arch/sh/include/asm/hugetlb.h @@ -89,4 +89,10 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_SH_HUGETLB_H */ diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h index 1770610..e99f4f7 100644 --- a/arch/sparc/include/asm/hugetlb.h +++ b/arch/sparc/include/asm/hugetlb.h @@ -82,4 +82,10 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_SPARC64_HUGETLB_H */ diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig index d5f2e57..2408a26 100644 --- a/arch/tile/Kconfig +++ b/arch/tile/Kconfig @@ -46,6 +46,14 @@ config NEED_PER_CPU_PAGE_FIRST_CHUNK config SYS_SUPPORTS_HUGETLBFS def_bool y +# Support for additional huge page sizes besides HPAGE_SIZE. +# The software support is currently only present in the TILE-Gx +# hypervisor. TILEPro in any case does not support page sizes +# larger than the default HPAGE_SIZE. +config HUGETLB_SUPER_PAGES + depends on HUGETLB_PAGE && TILEGX + def_bool y + config GENERIC_CLOCKEVENTS def_bool y diff --git a/arch/tile/include/asm/hugetlb.h b/arch/tile/include/asm/hugetlb.h index d396d18..9b62972 100644 --- a/arch/tile/include/asm/hugetlb.h +++ b/arch/tile/include/asm/hugetlb.h @@ -106,4 +106,26 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ +#ifdef CONFIG_HUGETLB_SUPER_PAGES + size_t pagesize = huge_page_size(hstate_vma(vma)); + if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) + entry = pte_mksuper(entry); +#endif + return entry; +} + +#ifdef CONFIG_HUGETLB_SUPER_PAGES +/* Sizes to scale up page size for PTEs with HV_PTE_SUPER bit. */ +enum { + HUGE_SHIFT_PGDIR = 0, + HUGE_SHIFT_PMD = 1, + HUGE_SHIFT_PAGE = 2, + HUGE_SHIFT_ENTRIES +}; +extern int huge_shift[HUGE_SHIFT_ENTRIES]; +#endif + #endif /* _ASM_TILE_HUGETLB_H */ diff --git a/arch/tile/include/asm/page.h b/arch/tile/include/asm/page.h index c750943..9d9131e 100644 --- a/arch/tile/include/asm/page.h +++ b/arch/tile/include/asm/page.h @@ -87,8 +87,7 @@ typedef HV_PTE pgprot_t; /* * User L2 page tables are managed as one L2 page table per page, * because we use the page allocator for them. This keeps the allocation - * simple and makes it potentially useful to implement HIGHPTE at some point. - * However, it's also inefficient, since L2 page tables are much smaller + * simple, but it's also inefficient, since L2 page tables are much smaller * than pages (currently 2KB vs 64KB). So we should revisit this. */ typedef struct page *pgtable_t; @@ -137,7 +136,7 @@ static inline __attribute_const__ int get_order(unsigned long size) #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) -#define HUGE_MAX_HSTATE 2 +#define HUGE_MAX_HSTATE 6 #ifdef CONFIG_HUGETLB_PAGE #define HAVE_ARCH_HUGETLB_UNMAPPED_AREA diff --git a/arch/tile/include/asm/pgtable.h b/arch/tile/include/asm/pgtable.h index ae43301..ff01704 100644 --- a/arch/tile/include/asm/pgtable.h +++ b/arch/tile/include/asm/pgtable.h @@ -72,6 +72,7 @@ extern void set_page_homes(void); #define _PAGE_PRESENT HV_PTE_PRESENT #define _PAGE_HUGE_PAGE HV_PTE_PAGE +#define _PAGE_SUPER_PAGE HV_PTE_SUPER #define _PAGE_READABLE HV_PTE_READABLE #define _PAGE_WRITABLE HV_PTE_WRITABLE #define _PAGE_EXECUTABLE HV_PTE_EXECUTABLE @@ -88,6 +89,7 @@ extern void set_page_homes(void); #define _PAGE_ALL (\ _PAGE_PRESENT | \ _PAGE_HUGE_PAGE | \ + _PAGE_SUPER_PAGE | \ _PAGE_READABLE | \ _PAGE_WRITABLE | \ _PAGE_EXECUTABLE | \ @@ -198,6 +200,7 @@ static inline void __pte_clear(pte_t *ptep) #define pte_write hv_pte_get_writable #define pte_exec hv_pte_get_executable #define pte_huge hv_pte_get_page +#define pte_super hv_pte_get_super #define pte_rdprotect hv_pte_clear_readable #define pte_exprotect hv_pte_clear_executable #define pte_mkclean hv_pte_clear_dirty @@ -210,6 +213,7 @@ static inline void __pte_clear(pte_t *ptep) #define pte_mkyoung hv_pte_set_accessed #define pte_mkwrite hv_pte_set_writable #define pte_mkhuge hv_pte_set_page +#define pte_mksuper hv_pte_set_super #define pte_special(pte) 0 #define pte_mkspecial(pte) (pte) @@ -339,13 +343,8 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) */ #define pgd_offset_k(address) pgd_offset(&init_mm, address) -#if defined(CONFIG_HIGHPTE) -extern pte_t *pte_offset_map(pmd_t *, unsigned long address); -#define pte_unmap(pte) kunmap_atomic(pte) -#else #define pte_offset_map(dir, address) pte_offset_kernel(dir, address) #define pte_unmap(pte) do { } while (0) -#endif /* Clear a non-executable kernel PTE and flush it from the TLB. */ #define kpte_clear_flush(ptep, vaddr) \ @@ -538,7 +537,8 @@ static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address) /* Support /proc/NN/pgtable API. */ struct seq_file; int arch_proc_pgtable_show(struct seq_file *m, struct mm_struct *mm, - unsigned long vaddr, pte_t *ptep, void **datap); unsigned long vaddr, unsigned long pagesize, + pte_t *ptep, void **datap); #endif /* !__ASSEMBLY__ */ diff --git a/arch/tile/include/asm/tlbflush.h b/arch/tile/include/asm/tlbflush.h index 96199d2..dcf91b2 100644 --- a/arch/tile/include/asm/tlbflush.h +++ b/arch/tile/include/asm/tlbflush.h @@ -38,16 +38,11 @@ DECLARE_PER_CPU(int, current_asid); /* The hypervisor tells us what ASIDs are available to us. */ extern int min_asid, max_asid; -static inline unsigned long hv_page_size(const struct vm_area_struct *vma) -{ - return (vma->vm_flags & VM_HUGETLB) ? HPAGE_SIZE : PAGE_SIZE; -} - /* Pass as vma pointer for non-executable mapping, if no vma available. */ -#define FLUSH_NONEXEC ((const struct vm_area_struct *)-1UL) +#define FLUSH_NONEXEC ((struct vm_area_struct *)-1UL) /* Flush a single user page on this cpu. */ -static inline void local_flush_tlb_page(const struct vm_area_struct *vma, +static inline void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long addr, unsigned long page_size) { @@ -60,7 +55,7 @@ static inline void local_flush_tlb_page(const struct vm_area_struct *vma, } /* Flush range of user pages on this cpu. */ -static inline void local_flush_tlb_pages(const struct vm_area_struct *vma, +static inline void local_flush_tlb_pages(struct vm_area_struct *vma, unsigned long addr, unsigned long page_size, unsigned long len) @@ -117,10 +112,10 @@ extern void flush_tlb_all(void); extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); extern void flush_tlb_current_task(void); extern void flush_tlb_mm(struct mm_struct *); -extern void flush_tlb_page(const struct vm_area_struct *, unsigned long); -extern void flush_tlb_page_mm(const struct vm_area_struct *, +extern void flush_tlb_page(struct vm_area_struct *, unsigned long); +extern void flush_tlb_page_mm(struct vm_area_struct *, struct mm_struct *, unsigned long); -extern void flush_tlb_range(const struct vm_area_struct *, +extern void flush_tlb_range(struct vm_area_struct *, unsigned long start, unsigned long end); #define flush_tlb() flush_tlb_current_task() diff --git a/arch/tile/include/hv/hypervisor.h b/arch/tile/include/hv/hypervisor.h index 16c18e4..3bc4045 100644 --- a/arch/tile/include/hv/hypervisor.h +++ b/arch/tile/include/hv/hypervisor.h @@ -66,6 +66,22 @@ #define HV_DEFAULT_PAGE_SIZE_LARGE \ (__HV_SIZE_ONE << HV_LOG2_DEFAULT_PAGE_SIZE_LARGE) +#if CHIP_VA_WIDTH() > 32 + +/** The log2 of the initial size of jumbo pages, in bytes. + * See HV_DEFAULT_PAGE_SIZE_JUMBO. + */ +#define HV_LOG2_DEFAULT_PAGE_SIZE_JUMBO 32 + +/** The initial size of jumbo pages, in bytes. This value should + * be verified at runtime by calling hv_sysconf(HV_SYSCONF_PAGE_SIZE_JUMBO). + * It may also be modified when installing a new context. + */ +#define HV_DEFAULT_PAGE_SIZE_JUMBO \ + (__HV_SIZE_ONE << HV_LOG2_DEFAULT_PAGE_SIZE_JUMBO) + +#endif + /** The log2 of the granularity at which page tables must be aligned; * in other words, the CPA for a page table must have this many zero * bits at the bottom of the address. @@ -284,8 +300,11 @@ #define HV_DISPATCH_GET_IPI_PTE 56 #endif +/** hv_set_pte_super_shift */ +#define HV_DISPATCH_SET_PTE_SUPER_SHIFT 57 + /** One more than the largest dispatch value */ -#define _HV_DISPATCH_END 57 +#define _HV_DISPATCH_END 58 #ifndef __ASSEMBLER__ @@ -413,6 +432,11 @@ typedef enum { */ HV_SYSCONF_VALID_PAGE_SIZES = 7, + /** The size of jumbo pages, in bytes. + * If no jumbo pages are available, zero will be returned. + */ + HV_SYSCONF_PAGE_SIZE_JUMBO = 8, + } HV_SysconfQuery; /** Offset to subtract from returned Kelvin temperature to get degrees @@ -690,6 +714,29 @@ int hv_install_context(HV_PhysAddr page_table, HV_PTE access, HV_ASID asid, #ifndef __ASSEMBLER__ + +/** Set the number of pages ganged together by HV_PTE_SUPER at a + * particular level of the page table. + * + * The current TILE-Gx hardware only supports powers of four + * (i.e. log2_count must be a multiple of two), and the requested + * "super" page size must be less than the span of the next level in + * the page table. The largest size that can be requested is 64GB. + * + * The shift value is initially "0" for all page table levels, + * indicating that the HV_PTE_SUPER bit is effectively ignored. + * + * If you change the count from one non-zero value to another, the + * hypervisor will flush the entire TLB and TSB to avoid confusion. + * + * @param level Page table level (0, 1, or 2) + * @param log2_count Base-2 log of the number of pages to gang together, + * i.e. how much to shift left the base page size for the super page size. + * @return Zero on success, or a hypervisor error code on failure. + */ +int hv_set_pte_super_shift(int level, int log2_count); + + /** Value returned from hv_inquire_context(). */ typedef struct { @@ -1875,8 +1922,9 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, #define HV_PTE_INDEX_USER 10 /**< Page is user-accessible */ #define HV_PTE_INDEX_ACCESSED 11 /**< Page has been accessed */ #define HV_PTE_INDEX_DIRTY 12 /**< Page has been written */ - /* Bits 13-15 are reserved for + /* Bits 13-14 are reserved for future use. */ +#define HV_PTE_INDEX_SUPER 15 /**< Pages ganged together for TLB */ #define HV_PTE_INDEX_MODE 16 /**< Page mode; see HV_PTE_MODE_xxx */ #define HV_PTE_MODE_BITS 3 /**< Number of bits in mode */ #define HV_PTE_INDEX_CLIENT2 19 /**< Page client state 2 */ @@ -1971,7 +2019,10 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, /** Does this PTE map a page? * - * If this bit is set in the level-1 page table, the entry should be + * If this bit is set in a level-0 page table, the entry should be + * interpreted as a level-2 page table entry mapping a jumbo page. + * + * If this bit is set in a level-1 page table, the entry should be * interpreted as a level-2 page table entry mapping a large page. * * This bit should not be modified by the client while PRESENT is set, as @@ -1981,6 +2032,18 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, */ #define HV_PTE_PAGE (__HV_PTE_ONE << HV_PTE_INDEX_PAGE) +/** Does this PTE implicitly reference multiple pages? + * + * If this bit is set in the page table (either in the level-2 page table, + * or in a higher level page table in conjunction with the PAGE bit) + * then the PTE specifies a range of contiguous pages, not a single page. + * The hv_set_pte_super_shift() allows you to specify the count for + * each level of the page table. + * + * Note: this bit is not supported on TILEPro systems. + */ +#define HV_PTE_SUPER (__HV_PTE_ONE << HV_PTE_INDEX_SUPER) + /** Is this a global (non-ASID) mapping? * * If this bit is set, the translations established by this PTE will @@ -2199,6 +2262,7 @@ hv_pte_clear_##name(HV_PTE pte) \ */ _HV_BIT(present, PRESENT) _HV_BIT(page, PAGE) +_HV_BIT(super, SUPER) _HV_BIT(client0, CLIENT0) _HV_BIT(client1, CLIENT1) _HV_BIT(client2, CLIENT2) diff --git a/arch/tile/kernel/hvglue.lds b/arch/tile/kernel/hvglue.lds index 2b7cd0a..d44c5a6 100644 --- a/arch/tile/kernel/hvglue.lds +++ b/arch/tile/kernel/hvglue.lds @@ -55,4 +55,5 @@ hv_store_mapping = TEXT_OFFSET + 0x106a0; hv_inquire_realpa = TEXT_OFFSET + 0x106c0; hv_flush_all = TEXT_OFFSET + 0x106e0; hv_get_ipi_pte = TEXT_OFFSET + 0x10700; -hv_glue_internals = TEXT_OFFSET + 0x10720; +hv_set_pte_super_shift = TEXT_OFFSET + 0x10720; +hv_glue_internals = TEXT_OFFSET + 0x10740; diff --git a/arch/tile/kernel/proc.c b/arch/tile/kernel/proc.c index 62d8208..663c97c 100644 --- a/arch/tile/kernel/proc.c +++ b/arch/tile/kernel/proc.c @@ -22,6 +22,7 @@ #include <linux/proc_fs.h> #include <linux/sysctl.h> #include <linux/hardirq.h> +#include <linux/hugetlb.h> #include <linux/mman.h> #include <asm/pgtable.h> #include <asm/processor.h> diff --git a/arch/tile/kernel/setup.c b/arch/tile/kernel/setup.c index 90251dc..825bc64 100644 --- a/arch/tile/kernel/setup.c +++ b/arch/tile/kernel/setup.c @@ -28,6 +28,7 @@ #include <linux/highmem.h> #include <linux/smp.h> #include <linux/timex.h> +#include <linux/hugetlb.h> #include <asm/setup.h> #include <asm/sections.h> #include <asm/cacheflush.h> @@ -49,9 +50,6 @@ char chip_model[64] __write_once; struct pglist_data node_data[MAX_NUMNODES] __read_mostly; EXPORT_SYMBOL(node_data); -/* We only create bootmem data on node 0. */ -static bootmem_data_t __initdata node0_bdata; - /* Information on the NUMA nodes that we compute early */ unsigned long __cpuinitdata node_start_pfn[MAX_NUMNODES]; unsigned long __cpuinitdata node_end_pfn[MAX_NUMNODES]; @@ -518,37 +516,96 @@ static void __init setup_memory(void) #endif } -static void __init setup_bootmem_allocator(void) +/* + * On 32-bit machines, we only put bootmem on the low controller, + * since PAs > 4GB can't be used in bootmem. In principle one could + * imagine, e.g., multiple 1 GB controllers all of which could support + * bootmem, but in practice using controllers this small isn't a + * particularly interesting scenario, so we just keep it simple and + * use only the first controller for bootmem on 32-bit machines. + */ +static inline int node_has_bootmem(int nid) +{ +#ifdef CONFIG_64BIT + return 1; +#else + return nid == 0; +#endif +} + +static inline unsigned long alloc_bootmem_pfn(int nid, + unsigned long size, + unsigned long goal) +{ + void *kva = __alloc_bootmem_node(NODE_DATA(nid), size, + PAGE_SIZE, goal); + unsigned long pfn = kaddr_to_pfn(kva); + BUG_ON(goal && PFN_PHYS(pfn) != goal); + return pfn; +} + +static void __init setup_bootmem_allocator_node(int i) { - unsigned long bootmap_size, first_alloc_pfn, last_alloc_pfn; + unsigned long start, end, mapsize, mapstart; + + if (node_has_bootmem(i)) { + NODE_DATA(i)->bdata = &bootmem_node_data[i]; + } else { + /* Share controller zero's bdata for now. */ + NODE_DATA(i)->bdata = &bootmem_node_data[0]; + return; + } - /* Provide a node 0 bdata. */ - NODE_DATA(0)->bdata = &node0_bdata; + /* Skip up to after the bss in node 0. */ + start = (i == 0) ? min_low_pfn : node_start_pfn[i]; -#ifdef CONFIG_PCI - /* Don't let boot memory alias the PCI region. */ - last_alloc_pfn = min(max_low_pfn, pci_reserve_start_pfn); + /* Only lowmem, if we're a HIGHMEM build. */ +#ifdef CONFIG_HIGHMEM + end = node_lowmem_end_pfn[i]; #else - last_alloc_pfn = max_low_pfn; + end = node_end_pfn[i]; #endif - /* - * Initialize the boot-time allocator (with low memory only): - * The first argument says where to put the bitmap, and the - * second says where the end of allocatable memory is. - */ - bootmap_size = init_bootmem(min_low_pfn, last_alloc_pfn); + /* No memory here. */ + if (end == start) + return; + /* Figure out where the bootmem bitmap is located. */ + mapsize = bootmem_bootmap_pages(end - start); + if (i == 0) { + /* Use some space right before the heap on node 0. */ + mapstart = start; + start += mapsize; + } else { + /* Allocate bitmap on node 0 to avoid page table issues. */ + mapstart = alloc_bootmem_pfn(0, PFN_PHYS(mapsize), 0); + } + + /* Initialize a node. */ + init_bootmem_node(NODE_DATA(i), mapstart, start, end); + + /* Free all the space back into the allocator. */ + free_bootmem(PFN_PHYS(start), PFN_PHYS(end - start)); + +#if defined(CONFIG_PCI) /* - * Let the bootmem allocator use all the space we've given it - * except for its own bitmap. + * Throw away any memory aliased by the PCI region. FIXME: this + * is a temporary hack to work around bug 10502, and needs to be + * fixed properly. */ - first_alloc_pfn = min_low_pfn + PFN_UP(bootmap_size); - if (first_alloc_pfn >= last_alloc_pfn) - early_panic("Not enough memory on controller 0 for bootmem\n"); + if (pci_reserve_start_pfn < end && pci_reserve_end_pfn > start) + reserve_bootmem(PFN_PHYS(pci_reserve_start_pfn), + PFN_PHYS(pci_reserve_end_pfn - + pci_reserve_start_pfn), + BOOTMEM_EXCLUSIVE); +#endif +} - free_bootmem(PFN_PHYS(first_alloc_pfn), - PFN_PHYS(last_alloc_pfn - first_alloc_pfn)); +static void __init setup_bootmem_allocator(void) +{ + int i; + for (i = 0; i < MAX_NUMNODES; ++i) + setup_bootmem_allocator_node(i); #ifdef CONFIG_KEXEC if (crashk_res.start != crashk_res.end) @@ -579,14 +636,6 @@ static int __init percpu_size(void) return size; } -static inline unsigned long alloc_bootmem_pfn(int size, unsigned long goal) -{ - void *kva = __alloc_bootmem(size, PAGE_SIZE, goal); - unsigned long pfn = kaddr_to_pfn(kva); - BUG_ON(goal && PFN_PHYS(pfn) != goal); - return pfn; -} - static void __init zone_sizes_init(void) { unsigned long zones_size[MAX_NR_ZONES] = { 0 }; @@ -624,21 +673,22 @@ static void __init zone_sizes_init(void) * though, there'll be no lowmem, so we just alloc_bootmem * the memmap. There will be no percpu memory either. */ - if (__pfn_to_highbits(start) == 0) { - /* In low PAs, allocate via bootmem. */ + if (i != 0 && cpu_isset(i, isolnodes)) { + node_memmap_pfn[i] = + alloc_bootmem_pfn(0, memmap_size, 0); + BUG_ON(node_percpu[i] != 0); + } else if (node_has_bootmem(start)) { unsigned long goal = 0; node_memmap_pfn[i] = - alloc_bootmem_pfn(memmap_size, goal); + alloc_bootmem_pfn(i, memmap_size, 0); if (kdata_huge) goal = PFN_PHYS(lowmem_end) - node_percpu[i]; if (node_percpu[i]) node_percpu_pfn[i] = - alloc_bootmem_pfn(node_percpu[i], goal); - } else if (cpu_isset(i, isolnodes)) { - node_memmap_pfn[i] = alloc_bootmem_pfn(memmap_size, 0); - BUG_ON(node_percpu[i] != 0); + alloc_bootmem_pfn(i, node_percpu[i], + goal); } else { - /* In high PAs, just reserve some pages. */ + /* In non-bootmem zones, just reserve some pages. */ node_memmap_pfn[i] = node_free_pfn[i]; node_free_pfn[i] += PFN_UP(memmap_size); if (!kdata_huge) { @@ -662,16 +712,9 @@ static void __init zone_sizes_init(void) zones_size[ZONE_NORMAL] = end - start; #endif - /* - * Everyone shares node 0's bootmem allocator, but - * we use alloc_remap(), above, to put the actual - * struct page array on the individual controllers, - * which is most of the data that we actually care about. - * We can't place bootmem allocators on the other - * controllers since the bootmem allocator can only - * operate on 32-bit physical addresses. - */ - NODE_DATA(i)->bdata = NODE_DATA(0)->bdata; + /* Take zone metadata from controller 0 if we're isolnode. */ + if (node_isset(i, isolnodes)) + NODE_DATA(i)->bdata = &bootmem_node_data[0]; free_area_init_node(i, zones_size, start, NULL); printk(KERN_DEBUG " Normal zone: %ld per-cpu pages\n", @@ -908,6 +951,15 @@ void __cpuinit setup_cpu(int boot) /* Reset the network state on this cpu. */ reset_network_state(); #endif + +#ifdef CONFIG_HUGETLB_SUPER_PAGES + /* Initialize hugepage support on this cpu. */ + if (!boot) { + int i; + for (i = 0; i < HUGE_SHIFT_ENTRIES; ++i) + hv_set_pte_super_shift(i, huge_shift[i]); + } +#endif } #ifdef CONFIG_BLK_DEV_INITRD diff --git a/arch/tile/kernel/tlb.c b/arch/tile/kernel/tlb.c index a5f241c..3fd54d5 100644 --- a/arch/tile/kernel/tlb.c +++ b/arch/tile/kernel/tlb.c @@ -15,6 +15,7 @@ #include <linux/cpumask.h> #include <linux/module.h> +#include <linux/hugetlb.h> #include <asm/tlbflush.h> #include <asm/homecache.h> #include <hv/hypervisor.h> @@ -49,25 +50,25 @@ void flush_tlb_current_task(void) flush_tlb_mm(current->mm); } -void flush_tlb_page_mm(const struct vm_area_struct *vma, struct mm_struct *mm, +void flush_tlb_page_mm(struct vm_area_struct *vma, struct mm_struct *mm, unsigned long va) { - unsigned long size = hv_page_size(vma); + unsigned long size = vma_kernel_pagesize(vma); int cache = (vma->vm_flags & VM_EXEC) ? HV_FLUSH_EVICT_L1I : 0; flush_remote(0, cache, mm_cpumask(mm), va, size, size, mm_cpumask(mm), NULL, 0); } -void flush_tlb_page(const struct vm_area_struct *vma, unsigned long va) +void flush_tlb_page(struct vm_area_struct *vma, unsigned long va) { flush_tlb_page_mm(vma, vma->vm_mm, va); } EXPORT_SYMBOL(flush_tlb_page); -void flush_tlb_range(const struct vm_area_struct *vma, +void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { - unsigned long size = hv_page_size(vma); + unsigned long size = vma_kernel_pagesize(vma); struct mm_struct *mm = vma->vm_mm; int cache = (vma->vm_flags & VM_EXEC) ? HV_FLUSH_EVICT_L1I : 0; flush_remote(0, cache, mm_cpumask(mm), start, end - start, size, diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index 5d10a74..7cea0fc 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -188,7 +188,7 @@ static pgd_t *get_current_pgd(void) HV_Context ctx = hv_inquire_context(); unsigned long pgd_pfn = ctx.page_table >> PAGE_SHIFT; struct page *pgd_page = pfn_to_page(pgd_pfn); - BUG_ON(PageHighMem(pgd_page)); /* oops, HIGHPTE? */ + BUG_ON(PageHighMem(pgd_page)); return (pgd_t *) __va(ctx.page_table); } diff --git a/arch/tile/mm/homecache.c b/arch/tile/mm/homecache.c index 499f737..dbcbdf7 100644 --- a/arch/tile/mm/homecache.c +++ b/arch/tile/mm/homecache.c @@ -30,6 +30,7 @@ #include <linux/cache.h> #include <linux/smp.h> #include <linux/module.h> +#include <linux/hugetlb.h> #include <asm/page.h> #include <asm/sections.h> diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c index 42cfcba..75716eb 100644 --- a/arch/tile/mm/hugetlbpage.c +++ b/arch/tile/mm/hugetlbpage.c @@ -27,85 +27,145 @@ #include <linux/mman.h> #include <asm/tlb.h> #include <asm/tlbflush.h> +#include <asm/setup.h> + +#ifdef CONFIG_HUGETLB_SUPER_PAGES +/* "Extra" page-size multipliers, one per level of the page table. */ +int huge_shift[HUGE_SHIFT_ENTRIES]; + +/* + * This routine is a hybrid of pte_alloc_map() and pte_alloc_kernel(). + * It assumes that L2 PTEs are never in HIGHMEM (we don't support that). + * It locks the user pagetable, and bumps up the mm->nr_ptes field, + * but otherwise allocate the page table using the kernel versions. + */ +static pte_t *pte_alloc_hugetlb(struct mm_struct *mm, pmd_t *pmd, + unsigned long address) +{ + pte_t *new; + + if (pmd_none(*pmd)) { + new = pte_alloc_one_kernel(mm, address); + if (!new) + return NULL; + + smp_wmb(); /* See comment in __pte_alloc */ + + spin_lock(&mm->page_table_lock); + if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ + mm->nr_ptes++; + pmd_populate_kernel(mm, pmd, new); + new = NULL; + } else + VM_BUG_ON(pmd_trans_splitting(*pmd)); + spin_unlock(&mm->page_table_lock); + if (new) + pte_free_kernel(mm, new); + } + + return pte_offset_kernel(pmd, address); +} +#endif pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz) { pgd_t *pgd; pud_t *pud; - pte_t *pte = NULL; - /* We do not yet support multiple huge page sizes. */ - BUG_ON(sz != PMD_SIZE); + addr &= -sz; /* Mask off any low bits in the address. */ pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); - if (pud) - pte = (pte_t *) pmd_alloc(mm, pud, addr); - BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); - return pte; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + if (sz >= PGDIR_SIZE) { + BUG_ON(sz != PGDIR_SIZE && + sz != PGDIR_SIZE << huge_shift[HUGE_SHIFT_PGDIR]); + return (pte_t *)pud; + } else { + pmd_t *pmd = pmd_alloc(mm, pud, addr); + if (sz >= PMD_SIZE) { + BUG_ON(sz != PMD_SIZE && + sz != (PMD_SIZE << huge_shift[HUGE_SHIFT_PMD])); + return (pte_t *)pmd; + } + else { + if (sz != PAGE_SIZE << huge_shift[HUGE_SHIFT_PAGE]) + panic("Unexpected page size %#lx\n", sz); + return pte_alloc_hugetlb(mm, pmd, addr); + } + } +#else + BUG_ON(sz != PMD_SIZE); + return (pte_t *) pmd_alloc(mm, pud, addr); +#endif } -pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) +static pte_t *get_pte(pte_t *base, int index, int level) { - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd = NULL; - - pgd = pgd_offset(mm, addr); - if (pgd_present(*pgd)) { - pud = pud_offset(pgd, addr); - if (pud_present(*pud)) - pmd = pmd_offset(pud, addr); + pte_t *ptep = base + index; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + if (!pte_present(*ptep) && huge_shift[level] != 0) { + unsigned long mask = -1UL << huge_shift[level]; + pte_t *super_ptep = base + (index & mask); + pte_t pte = *super_ptep; + if (pte_present(pte) && pte_super(pte)) + ptep = super_ptep; } - return (pte_t *) pmd; +#endif + return ptep; } -#ifdef HUGETLB_TEST -struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, - int write) +pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) { - unsigned long start = address; - int length = 1; - int nr; - struct page *page; - struct vm_area_struct *vma; - - vma = find_vma(mm, addr); - if (!vma || !is_vm_hugetlb_page(vma)) - return ERR_PTR(-EINVAL); - - pte = huge_pte_offset(mm, address); - - /* hugetlb should be locked, and hence, prefaulted */ - WARN_ON(!pte || pte_none(*pte)); + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + pte_t *pte; +#endif - page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; + /* Get the top-level page table entry. */ + pgd = (pgd_t *)get_pte((pte_t *)mm->pgd, pgd_index(addr), 0); + if (!pgd_present(*pgd)) + return NULL; - WARN_ON(!PageHead(page)); + /* We don't have four levels. */ + pud = pud_offset(pgd, addr); +#ifndef __PAGETABLE_PUD_FOLDED +# error support fourth page table level +#endif - return page; -} + /* Check for an L0 huge PTE, if we have three levels. */ +#ifndef __PAGETABLE_PMD_FOLDED + if (pud_huge(*pud)) + return (pte_t *)pud; -int pmd_huge(pmd_t pmd) -{ - return 0; -} + pmd = (pmd_t *)get_pte((pte_t *)pud_page_vaddr(*pud), + pmd_index(addr), 1); + if (!pmd_present(*pmd)) + return NULL; +#else + pmd = pmd_offset(pud, addr); +#endif -int pud_huge(pud_t pud) -{ - return 0; -} + /* Check for an L1 huge PTE. */ + if (pmd_huge(*pmd)) + return (pte_t *)pmd; + +#ifdef CONFIG_HUGETLB_SUPER_PAGES + /* Check for an L2 huge PTE. */ + pte = get_pte((pte_t *)pmd_page_vaddr(*pmd), pte_index(addr), 2); + if (!pte_present(*pte)) + return NULL; + if (pte_super(*pte)) + return pte; +#endif -struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, - pmd_t *pmd, int write) -{ return NULL; } -#else - struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) { @@ -149,8 +209,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) return 0; } -#endif - #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr, unsigned long len, @@ -323,20 +381,77 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, pgoff, flags); } -static __init int setup_hugepagesz(char *opt) +#ifdef CONFIG_HUGETLB_SUPER_PAGES +static void add_super_size(unsigned long ps, int level, int base_shift) { - unsigned long ps = memparse(opt, &opt); - if (ps == PMD_SIZE) { - hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT); - } else if (ps == PUD_SIZE) { - hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); + int log_ps = __builtin_ctzl(ps); + if ((1UL << log_ps) != ps || (log_ps & 1) != 0) { + pr_warn("Not enabling %ld byte huge pages;" + " must be a power of four.\n", ps); + return; + } + if (log_ps != base_shift) { + if (huge_shift[level] != 0) { + int old_shift = base_shift + huge_shift[level]; + pr_warn("Not enabling %ld MB huge pages;" + " already have size %ld MB.\n", + ps >> 20, (1UL << old_shift) >> 20); + return; + } + if (hv_set_pte_super_shift(level, log_ps - base_shift) != 0) { + pr_warn("Not enabling %ld MB huge pages;" + " no hypervisor support.\n", ps >> 20); + return; + } + printk(KERN_DEBUG "Enabled %ld MB huge pages\n", ps >> 20); + huge_shift[level] = log_ps - base_shift; + } + hugetlb_add_hstate(log_ps - PAGE_SHIFT); +} + +static __init int __setup_hugepagesz(unsigned long ps) +{ + if (ps > 64*1024*1024*1024UL) { + pr_warn("Not enabling %ld MB huge pages;" + " largest legal value is 64 GB .\n", ps >> 20); + } + else if (ps >= PUD_SIZE) { + static long hv_jpage_size; + if (hv_jpage_size == 0) + hv_jpage_size = hv_sysconf(HV_SYSCONF_PAGE_SIZE_JUMBO); + if (hv_jpage_size != PUD_SIZE) { + pr_warn("Not enabling >= %ld MB huge pages:" + " hypervisor reports size %ld\n", + PUD_SIZE >> 20, hv_jpage_size); + } + add_super_size(ps, 0, PUD_SHIFT); + } else if (ps >= PMD_SIZE) { + add_super_size(ps, 1, PMD_SHIFT); + } else if (ps > PAGE_SIZE) { + add_super_size(ps, 2, PAGE_SHIFT); } else { - pr_err("hugepagesz: Unsupported page size %lu M\n", - ps >> 20); - return 0; + pr_err("hugepagesz: Unsupported page size %ld\n", ps); } return 1; } + +bool saw_hugepagesz; + +static __init int setup_hugepagesz(char *opt) +{ + saw_hugepagesz = true; + return __setup_hugepagesz(memparse(opt, NULL)); +} __setup("hugepagesz=", setup_hugepagesz); +/* Provide 1MB size as a standard default if nothing specified. */ +static __init int add_default_hugepagesz(void) +{ + if (!saw_hugepagesz) + __setup_hugepagesz(1 * 1024 * 1024UL); + return 1; +} +arch_initcall(add_default_hugepagesz); +#endif + #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/ diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c index 6119f46..5276f05 100644 --- a/arch/tile/mm/init.c +++ b/arch/tile/mm/init.c @@ -704,6 +704,7 @@ static void __init permanent_kmaps_init(pgd_t *pgd_base) #endif /* CONFIG_HIGHMEM */ +#ifndef CONFIG_64BIT static void __init init_free_pfn_range(unsigned long start, unsigned long end) { unsigned long pfn; @@ -776,6 +777,7 @@ static void __init set_non_bootmem_pages_init(void) init_free_pfn_range(start, end); } } +#endif /* * paging_init() sets up the page tables - note that all of lowmem is @@ -864,8 +866,10 @@ void __init mem_init(void) /* this will put all bootmem onto the freelists */ totalram_pages += free_all_bootmem(); +#ifndef CONFIG_64BIT /* count all remaining LOWMEM and give all HIGHMEM to page allocator */ set_non_bootmem_pages_init(); +#endif codesize = (unsigned long)&_etext - (unsigned long)&_text; datasize = (unsigned long)&_end - (unsigned long)&_sdata; diff --git a/arch/tile/mm/pgtable.c b/arch/tile/mm/pgtable.c index 9c6985f..e52bfc8 100644 --- a/arch/tile/mm/pgtable.c +++ b/arch/tile/mm/pgtable.c @@ -133,15 +133,6 @@ void __set_fixmap(enum fixed_addresses idx, unsigned long phys, pgprot_t flags) set_pte_pfn(address, phys >> PAGE_SHIFT, flags); } -#if defined(CONFIG_HIGHPTE) -pte_t *_pte_offset_map(pmd_t *dir, unsigned long address) -{ - pte_t *pte = kmap_atomic(pmd_page(*dir)) + - (pmd_ptfn(*dir) << HV_LOG2_PAGE_TABLE_ALIGN) & ~PAGE_MASK; - return &pte[pte_index(address)]; -} -#endif - /** * shatter_huge_page() - ensure a given address is mapped by a small page. * @@ -297,10 +288,6 @@ struct page *pgtable_alloc_one(struct mm_struct *mm, unsigned long address, struct page *p; int i; -#ifdef CONFIG_HIGHPTE - flags |= __GFP_HIGHMEM; -#endif - p = alloc_pages(flags, L2_USER_PGTABLE_ORDER); if (p == NULL) return NULL; diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h index 439a9ac..ec832e5 100644 --- a/arch/x86/include/asm/hugetlb.h +++ b/arch/x86/include/asm/hugetlb.h @@ -90,4 +90,10 @@ static inline void arch_release_hugepage(struct page *page) { } +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} + #endif /* _ASM_X86_HUGETLB_H */ diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a876871..1871753 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2123,6 +2123,7 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, } entry = pte_mkyoung(entry); entry = pte_mkhuge(entry); + entry = arch_make_huge_pte(entry, vma, page, writable); return entry; } -- 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH v2] arch/tile: support multiple huge page sizes dynamically 2012-03-30 19:37 ` [PATCH v2] arch/tile: support multiple huge page sizes dynamically Chris Metcalf @ 2012-03-31 14:03 ` Hillf Danton 2012-03-30 19:37 ` [PATCH v3] " Chris Metcalf 0 siblings, 1 reply; 17+ messages in thread From: Hillf Danton @ 2012-03-31 14:03 UTC (permalink / raw) To: Chris Metcalf Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Sat, Mar 31, 2012 at 3:37 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: > > Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> > --- > This change incorporates Hillf Danton's suggestion to not use a > macro for arch_make_huge_pte() but instead use the standard hugetlb > model of providing an empty inline function for every other platform. > Oh my god. First my bad, no clear comment provided:( What I meant actually is to add something in include/asm-generic/pgtable.h #ifndef __HAVE_ARCH_FOO_BAR the_default_foo_bar() { } #endif or it is too hard to add default foo_bar for each arch involved. Say sorry again Hillf -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v3] arch/tile: support multiple huge page sizes dynamically 2012-03-31 14:03 ` Hillf Danton @ 2012-03-30 19:37 ` Chris Metcalf 2012-04-01 12:33 ` Hillf Danton 0 siblings, 1 reply; 17+ messages in thread From: Chris Metcalf @ 2012-03-30 19:37 UTC (permalink / raw) To: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins, Hillf Danton This change adds support for a new "super" bit in the PTE, and a new arch_make_huge_pte() method called from make_huge_pte(). The Tilera hypervisor sees the bit set at a given level of the page table and gangs together 4, 16, or 64 consecutive pages from that level of the hierarchy to create a larger TLB entry. One extra "super" page size can be specified at each of the three levels of the page table hierarchy on tilegx, using the "hugepagesz" argument on the boot command line. A new hypervisor API is added to allow Linux to tell the hypervisor how many PTEs to gang together at each level of the page table. To allow pre-allocating huge pages larger than the buddy allocator can handle, this change modifies the Tilera bootmem support to put all of memory on tilegx platforms into bootmem. As part of this change I eliminate the vestigial CONFIG_HIGHPTE support, which never worked anyway, and eliminate the hv_page_size() API in favor of the standard vma_kernel_pagesize() API. Reviewed-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> --- This version of the patch adds a generic no-op definition to <linux/hugetlb.h> if "arch_make_huge_pte" is not #defined. I'm following Linus's model in https://lkml.org/lkml/2012/1/19/443 which says you create the inline, then "#define func func" to indicate that the function exists. Hillf, let me know if you want to provide an Acked-by, or I'll leave it as Reviewed-by. I'm glad you didn't like the v2 patch; I always thought having every architecture provide their own no-op was a bit of a mysterious style choice. :-) Thanks! arch/tile/Kconfig | 8 ++ arch/tile/include/asm/hugetlb.h | 21 ++++ arch/tile/include/asm/page.h | 5 +- arch/tile/include/asm/pgtable.h | 12 +- arch/tile/include/asm/tlbflush.h | 17 +-- arch/tile/include/hv/hypervisor.h | 70 ++++++++++- arch/tile/kernel/hvglue.lds | 3 +- arch/tile/kernel/proc.c | 1 + arch/tile/kernel/setup.c | 152 ++++++++++++++++-------- arch/tile/kernel/tlb.c | 11 +- arch/tile/mm/fault.c | 2 +- arch/tile/mm/homecache.c | 1 + arch/tile/mm/hugetlbpage.c | 241 +++++++++++++++++++++++++++---------- arch/tile/mm/init.c | 4 + arch/tile/mm/pgtable.c | 13 -- include/linux/hugetlb.h | 8 ++ mm/hugetlb.c | 1 + 17 files changed, 414 insertions(+), 156 deletions(-) diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig index d5f2e57..2408a26 100644 --- a/arch/tile/Kconfig +++ b/arch/tile/Kconfig @@ -46,6 +46,14 @@ config NEED_PER_CPU_PAGE_FIRST_CHUNK config SYS_SUPPORTS_HUGETLBFS def_bool y +# Support for additional huge page sizes besides HPAGE_SIZE. +# The software support is currently only present in the TILE-Gx +# hypervisor. TILEPro in any case does not support page sizes +# larger than the default HPAGE_SIZE. +config HUGETLB_SUPER_PAGES + depends on HUGETLB_PAGE && TILEGX + def_bool y + config GENERIC_CLOCKEVENTS def_bool y diff --git a/arch/tile/include/asm/hugetlb.h b/arch/tile/include/asm/hugetlb.h index d396d18..b204238 100644 --- a/arch/tile/include/asm/hugetlb.h +++ b/arch/tile/include/asm/hugetlb.h @@ -106,4 +106,25 @@ static inline void arch_release_hugepage(struct page *page) { } +#ifdef CONFIG_HUGETLB_SUPER_PAGES +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + size_t pagesize = huge_page_size(hstate_vma(vma)); + if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) + entry = pte_mksuper(entry); + return entry; +} +#define arch_make_huge_pte arch_make_huge_pte + +/* Sizes to scale up page size for PTEs with HV_PTE_SUPER bit. */ +enum { + HUGE_SHIFT_PGDIR = 0, + HUGE_SHIFT_PMD = 1, + HUGE_SHIFT_PAGE = 2, + HUGE_SHIFT_ENTRIES +}; +extern int huge_shift[HUGE_SHIFT_ENTRIES]; +#endif + #endif /* _ASM_TILE_HUGETLB_H */ diff --git a/arch/tile/include/asm/page.h b/arch/tile/include/asm/page.h index c750943..9d9131e 100644 --- a/arch/tile/include/asm/page.h +++ b/arch/tile/include/asm/page.h @@ -87,8 +87,7 @@ typedef HV_PTE pgprot_t; /* * User L2 page tables are managed as one L2 page table per page, * because we use the page allocator for them. This keeps the allocation - * simple and makes it potentially useful to implement HIGHPTE at some point. - * However, it's also inefficient, since L2 page tables are much smaller + * simple, but it's also inefficient, since L2 page tables are much smaller * than pages (currently 2KB vs 64KB). So we should revisit this. */ typedef struct page *pgtable_t; @@ -137,7 +136,7 @@ static inline __attribute_const__ int get_order(unsigned long size) #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) -#define HUGE_MAX_HSTATE 2 +#define HUGE_MAX_HSTATE 6 #ifdef CONFIG_HUGETLB_PAGE #define HAVE_ARCH_HUGETLB_UNMAPPED_AREA diff --git a/arch/tile/include/asm/pgtable.h b/arch/tile/include/asm/pgtable.h index ae43301..ff01704 100644 --- a/arch/tile/include/asm/pgtable.h +++ b/arch/tile/include/asm/pgtable.h @@ -72,6 +72,7 @@ extern void set_page_homes(void); #define _PAGE_PRESENT HV_PTE_PRESENT #define _PAGE_HUGE_PAGE HV_PTE_PAGE +#define _PAGE_SUPER_PAGE HV_PTE_SUPER #define _PAGE_READABLE HV_PTE_READABLE #define _PAGE_WRITABLE HV_PTE_WRITABLE #define _PAGE_EXECUTABLE HV_PTE_EXECUTABLE @@ -88,6 +89,7 @@ extern void set_page_homes(void); #define _PAGE_ALL (\ _PAGE_PRESENT | \ _PAGE_HUGE_PAGE | \ + _PAGE_SUPER_PAGE | \ _PAGE_READABLE | \ _PAGE_WRITABLE | \ _PAGE_EXECUTABLE | \ @@ -198,6 +200,7 @@ static inline void __pte_clear(pte_t *ptep) #define pte_write hv_pte_get_writable #define pte_exec hv_pte_get_executable #define pte_huge hv_pte_get_page +#define pte_super hv_pte_get_super #define pte_rdprotect hv_pte_clear_readable #define pte_exprotect hv_pte_clear_executable #define pte_mkclean hv_pte_clear_dirty @@ -210,6 +213,7 @@ static inline void __pte_clear(pte_t *ptep) #define pte_mkyoung hv_pte_set_accessed #define pte_mkwrite hv_pte_set_writable #define pte_mkhuge hv_pte_set_page +#define pte_mksuper hv_pte_set_super #define pte_special(pte) 0 #define pte_mkspecial(pte) (pte) @@ -339,13 +343,8 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) */ #define pgd_offset_k(address) pgd_offset(&init_mm, address) -#if defined(CONFIG_HIGHPTE) -extern pte_t *pte_offset_map(pmd_t *, unsigned long address); -#define pte_unmap(pte) kunmap_atomic(pte) -#else #define pte_offset_map(dir, address) pte_offset_kernel(dir, address) #define pte_unmap(pte) do { } while (0) -#endif /* Clear a non-executable kernel PTE and flush it from the TLB. */ #define kpte_clear_flush(ptep, vaddr) \ @@ -538,7 +537,8 @@ static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address) /* Support /proc/NN/pgtable API. */ struct seq_file; int arch_proc_pgtable_show(struct seq_file *m, struct mm_struct *mm, - unsigned long vaddr, pte_t *ptep, void **datap); + unsigned long vaddr, unsigned long pagesize, + pte_t *ptep, void **datap); #endif /* !__ASSEMBLY__ */ diff --git a/arch/tile/include/asm/tlbflush.h b/arch/tile/include/asm/tlbflush.h index 96199d2..dcf91b2 100644 --- a/arch/tile/include/asm/tlbflush.h +++ b/arch/tile/include/asm/tlbflush.h @@ -38,16 +38,11 @@ DECLARE_PER_CPU(int, current_asid); /* The hypervisor tells us what ASIDs are available to us. */ extern int min_asid, max_asid; -static inline unsigned long hv_page_size(const struct vm_area_struct *vma) -{ - return (vma->vm_flags & VM_HUGETLB) ? HPAGE_SIZE : PAGE_SIZE; -} - /* Pass as vma pointer for non-executable mapping, if no vma available. */ -#define FLUSH_NONEXEC ((const struct vm_area_struct *)-1UL) +#define FLUSH_NONEXEC ((struct vm_area_struct *)-1UL) /* Flush a single user page on this cpu. */ -static inline void local_flush_tlb_page(const struct vm_area_struct *vma, +static inline void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long addr, unsigned long page_size) { @@ -60,7 +55,7 @@ static inline void local_flush_tlb_page(const struct vm_area_struct *vma, } /* Flush range of user pages on this cpu. */ -static inline void local_flush_tlb_pages(const struct vm_area_struct *vma, +static inline void local_flush_tlb_pages(struct vm_area_struct *vma, unsigned long addr, unsigned long page_size, unsigned long len) @@ -117,10 +112,10 @@ extern void flush_tlb_all(void); extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); extern void flush_tlb_current_task(void); extern void flush_tlb_mm(struct mm_struct *); -extern void flush_tlb_page(const struct vm_area_struct *, unsigned long); -extern void flush_tlb_page_mm(const struct vm_area_struct *, +extern void flush_tlb_page(struct vm_area_struct *, unsigned long); +extern void flush_tlb_page_mm(struct vm_area_struct *, struct mm_struct *, unsigned long); -extern void flush_tlb_range(const struct vm_area_struct *, +extern void flush_tlb_range(struct vm_area_struct *, unsigned long start, unsigned long end); #define flush_tlb() flush_tlb_current_task() diff --git a/arch/tile/include/hv/hypervisor.h b/arch/tile/include/hv/hypervisor.h index 16c18e4..3bc4045 100644 --- a/arch/tile/include/hv/hypervisor.h +++ b/arch/tile/include/hv/hypervisor.h @@ -66,6 +66,22 @@ #define HV_DEFAULT_PAGE_SIZE_LARGE \ (__HV_SIZE_ONE << HV_LOG2_DEFAULT_PAGE_SIZE_LARGE) +#if CHIP_VA_WIDTH() > 32 + +/** The log2 of the initial size of jumbo pages, in bytes. + * See HV_DEFAULT_PAGE_SIZE_JUMBO. + */ +#define HV_LOG2_DEFAULT_PAGE_SIZE_JUMBO 32 + +/** The initial size of jumbo pages, in bytes. This value should + * be verified at runtime by calling hv_sysconf(HV_SYSCONF_PAGE_SIZE_JUMBO). + * It may also be modified when installing a new context. + */ +#define HV_DEFAULT_PAGE_SIZE_JUMBO \ + (__HV_SIZE_ONE << HV_LOG2_DEFAULT_PAGE_SIZE_JUMBO) + +#endif + /** The log2 of the granularity at which page tables must be aligned; * in other words, the CPA for a page table must have this many zero * bits at the bottom of the address. @@ -284,8 +300,11 @@ #define HV_DISPATCH_GET_IPI_PTE 56 #endif +/** hv_set_pte_super_shift */ +#define HV_DISPATCH_SET_PTE_SUPER_SHIFT 57 + /** One more than the largest dispatch value */ -#define _HV_DISPATCH_END 57 +#define _HV_DISPATCH_END 58 #ifndef __ASSEMBLER__ @@ -413,6 +432,11 @@ typedef enum { */ HV_SYSCONF_VALID_PAGE_SIZES = 7, + /** The size of jumbo pages, in bytes. + * If no jumbo pages are available, zero will be returned. + */ + HV_SYSCONF_PAGE_SIZE_JUMBO = 8, + } HV_SysconfQuery; /** Offset to subtract from returned Kelvin temperature to get degrees @@ -690,6 +714,29 @@ int hv_install_context(HV_PhysAddr page_table, HV_PTE access, HV_ASID asid, #ifndef __ASSEMBLER__ + +/** Set the number of pages ganged together by HV_PTE_SUPER at a + * particular level of the page table. + * + * The current TILE-Gx hardware only supports powers of four + * (i.e. log2_count must be a multiple of two), and the requested + * "super" page size must be less than the span of the next level in + * the page table. The largest size that can be requested is 64GB. + * + * The shift value is initially "0" for all page table levels, + * indicating that the HV_PTE_SUPER bit is effectively ignored. + * + * If you change the count from one non-zero value to another, the + * hypervisor will flush the entire TLB and TSB to avoid confusion. + * + * @param level Page table level (0, 1, or 2) + * @param log2_count Base-2 log of the number of pages to gang together, + * i.e. how much to shift left the base page size for the super page size. + * @return Zero on success, or a hypervisor error code on failure. + */ +int hv_set_pte_super_shift(int level, int log2_count); + + /** Value returned from hv_inquire_context(). */ typedef struct { @@ -1875,8 +1922,9 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, #define HV_PTE_INDEX_USER 10 /**< Page is user-accessible */ #define HV_PTE_INDEX_ACCESSED 11 /**< Page has been accessed */ #define HV_PTE_INDEX_DIRTY 12 /**< Page has been written */ - /* Bits 13-15 are reserved for + /* Bits 13-14 are reserved for future use. */ +#define HV_PTE_INDEX_SUPER 15 /**< Pages ganged together for TLB */ #define HV_PTE_INDEX_MODE 16 /**< Page mode; see HV_PTE_MODE_xxx */ #define HV_PTE_MODE_BITS 3 /**< Number of bits in mode */ #define HV_PTE_INDEX_CLIENT2 19 /**< Page client state 2 */ @@ -1971,7 +2019,10 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, /** Does this PTE map a page? * - * If this bit is set in the level-1 page table, the entry should be + * If this bit is set in a level-0 page table, the entry should be + * interpreted as a level-2 page table entry mapping a jumbo page. + * + * If this bit is set in a level-1 page table, the entry should be * interpreted as a level-2 page table entry mapping a large page. * * This bit should not be modified by the client while PRESENT is set, as @@ -1981,6 +2032,18 @@ int hv_flush_remote(HV_PhysAddr cache_pa, unsigned long cache_control, */ #define HV_PTE_PAGE (__HV_PTE_ONE << HV_PTE_INDEX_PAGE) +/** Does this PTE implicitly reference multiple pages? + * + * If this bit is set in the page table (either in the level-2 page table, + * or in a higher level page table in conjunction with the PAGE bit) + * then the PTE specifies a range of contiguous pages, not a single page. + * The hv_set_pte_super_shift() allows you to specify the count for + * each level of the page table. + * + * Note: this bit is not supported on TILEPro systems. + */ +#define HV_PTE_SUPER (__HV_PTE_ONE << HV_PTE_INDEX_SUPER) + /** Is this a global (non-ASID) mapping? * * If this bit is set, the translations established by this PTE will @@ -2199,6 +2262,7 @@ hv_pte_clear_##name(HV_PTE pte) \ */ _HV_BIT(present, PRESENT) _HV_BIT(page, PAGE) +_HV_BIT(super, SUPER) _HV_BIT(client0, CLIENT0) _HV_BIT(client1, CLIENT1) _HV_BIT(client2, CLIENT2) diff --git a/arch/tile/kernel/hvglue.lds b/arch/tile/kernel/hvglue.lds index 2b7cd0a..d44c5a6 100644 --- a/arch/tile/kernel/hvglue.lds +++ b/arch/tile/kernel/hvglue.lds @@ -55,4 +55,5 @@ hv_store_mapping = TEXT_OFFSET + 0x106a0; hv_inquire_realpa = TEXT_OFFSET + 0x106c0; hv_flush_all = TEXT_OFFSET + 0x106e0; hv_get_ipi_pte = TEXT_OFFSET + 0x10700; -hv_glue_internals = TEXT_OFFSET + 0x10720; +hv_set_pte_super_shift = TEXT_OFFSET + 0x10720; +hv_glue_internals = TEXT_OFFSET + 0x10740; diff --git a/arch/tile/kernel/proc.c b/arch/tile/kernel/proc.c index 62d8208..663c97c 100644 --- a/arch/tile/kernel/proc.c +++ b/arch/tile/kernel/proc.c @@ -22,6 +22,7 @@ #include <linux/proc_fs.h> #include <linux/sysctl.h> #include <linux/hardirq.h> +#include <linux/hugetlb.h> #include <linux/mman.h> #include <asm/pgtable.h> #include <asm/processor.h> diff --git a/arch/tile/kernel/setup.c b/arch/tile/kernel/setup.c index 90251dc..825bc64 100644 --- a/arch/tile/kernel/setup.c +++ b/arch/tile/kernel/setup.c @@ -28,6 +28,7 @@ #include <linux/highmem.h> #include <linux/smp.h> #include <linux/timex.h> +#include <linux/hugetlb.h> #include <asm/setup.h> #include <asm/sections.h> #include <asm/cacheflush.h> @@ -49,9 +50,6 @@ char chip_model[64] __write_once; struct pglist_data node_data[MAX_NUMNODES] __read_mostly; EXPORT_SYMBOL(node_data); -/* We only create bootmem data on node 0. */ -static bootmem_data_t __initdata node0_bdata; - /* Information on the NUMA nodes that we compute early */ unsigned long __cpuinitdata node_start_pfn[MAX_NUMNODES]; unsigned long __cpuinitdata node_end_pfn[MAX_NUMNODES]; @@ -518,37 +516,96 @@ static void __init setup_memory(void) #endif } -static void __init setup_bootmem_allocator(void) +/* + * On 32-bit machines, we only put bootmem on the low controller, + * since PAs > 4GB can't be used in bootmem. In principle one could + * imagine, e.g., multiple 1 GB controllers all of which could support + * bootmem, but in practice using controllers this small isn't a + * particularly interesting scenario, so we just keep it simple and + * use only the first controller for bootmem on 32-bit machines. + */ +static inline int node_has_bootmem(int nid) +{ +#ifdef CONFIG_64BIT + return 1; +#else + return nid == 0; +#endif +} + +static inline unsigned long alloc_bootmem_pfn(int nid, + unsigned long size, + unsigned long goal) +{ + void *kva = __alloc_bootmem_node(NODE_DATA(nid), size, + PAGE_SIZE, goal); + unsigned long pfn = kaddr_to_pfn(kva); + BUG_ON(goal && PFN_PHYS(pfn) != goal); + return pfn; +} + +static void __init setup_bootmem_allocator_node(int i) { - unsigned long bootmap_size, first_alloc_pfn, last_alloc_pfn; + unsigned long start, end, mapsize, mapstart; + + if (node_has_bootmem(i)) { + NODE_DATA(i)->bdata = &bootmem_node_data[i]; + } else { + /* Share controller zero's bdata for now. */ + NODE_DATA(i)->bdata = &bootmem_node_data[0]; + return; + } - /* Provide a node 0 bdata. */ - NODE_DATA(0)->bdata = &node0_bdata; + /* Skip up to after the bss in node 0. */ + start = (i == 0) ? min_low_pfn : node_start_pfn[i]; -#ifdef CONFIG_PCI - /* Don't let boot memory alias the PCI region. */ - last_alloc_pfn = min(max_low_pfn, pci_reserve_start_pfn); + /* Only lowmem, if we're a HIGHMEM build. */ +#ifdef CONFIG_HIGHMEM + end = node_lowmem_end_pfn[i]; #else - last_alloc_pfn = max_low_pfn; + end = node_end_pfn[i]; #endif - /* - * Initialize the boot-time allocator (with low memory only): - * The first argument says where to put the bitmap, and the - * second says where the end of allocatable memory is. - */ - bootmap_size = init_bootmem(min_low_pfn, last_alloc_pfn); + /* No memory here. */ + if (end == start) + return; + /* Figure out where the bootmem bitmap is located. */ + mapsize = bootmem_bootmap_pages(end - start); + if (i == 0) { + /* Use some space right before the heap on node 0. */ + mapstart = start; + start += mapsize; + } else { + /* Allocate bitmap on node 0 to avoid page table issues. */ + mapstart = alloc_bootmem_pfn(0, PFN_PHYS(mapsize), 0); + } + + /* Initialize a node. */ + init_bootmem_node(NODE_DATA(i), mapstart, start, end); + + /* Free all the space back into the allocator. */ + free_bootmem(PFN_PHYS(start), PFN_PHYS(end - start)); + +#if defined(CONFIG_PCI) /* - * Let the bootmem allocator use all the space we've given it - * except for its own bitmap. + * Throw away any memory aliased by the PCI region. FIXME: this + * is a temporary hack to work around bug 10502, and needs to be + * fixed properly. */ - first_alloc_pfn = min_low_pfn + PFN_UP(bootmap_size); - if (first_alloc_pfn >= last_alloc_pfn) - early_panic("Not enough memory on controller 0 for bootmem\n"); + if (pci_reserve_start_pfn < end && pci_reserve_end_pfn > start) + reserve_bootmem(PFN_PHYS(pci_reserve_start_pfn), + PFN_PHYS(pci_reserve_end_pfn - + pci_reserve_start_pfn), + BOOTMEM_EXCLUSIVE); +#endif +} - free_bootmem(PFN_PHYS(first_alloc_pfn), - PFN_PHYS(last_alloc_pfn - first_alloc_pfn)); +static void __init setup_bootmem_allocator(void) +{ + int i; + for (i = 0; i < MAX_NUMNODES; ++i) + setup_bootmem_allocator_node(i); #ifdef CONFIG_KEXEC if (crashk_res.start != crashk_res.end) @@ -579,14 +636,6 @@ static int __init percpu_size(void) return size; } -static inline unsigned long alloc_bootmem_pfn(int size, unsigned long goal) -{ - void *kva = __alloc_bootmem(size, PAGE_SIZE, goal); - unsigned long pfn = kaddr_to_pfn(kva); - BUG_ON(goal && PFN_PHYS(pfn) != goal); - return pfn; -} - static void __init zone_sizes_init(void) { unsigned long zones_size[MAX_NR_ZONES] = { 0 }; @@ -624,21 +673,22 @@ static void __init zone_sizes_init(void) * though, there'll be no lowmem, so we just alloc_bootmem * the memmap. There will be no percpu memory either. */ - if (__pfn_to_highbits(start) == 0) { - /* In low PAs, allocate via bootmem. */ + if (i != 0 && cpu_isset(i, isolnodes)) { + node_memmap_pfn[i] = + alloc_bootmem_pfn(0, memmap_size, 0); + BUG_ON(node_percpu[i] != 0); + } else if (node_has_bootmem(start)) { unsigned long goal = 0; node_memmap_pfn[i] = - alloc_bootmem_pfn(memmap_size, goal); + alloc_bootmem_pfn(i, memmap_size, 0); if (kdata_huge) goal = PFN_PHYS(lowmem_end) - node_percpu[i]; if (node_percpu[i]) node_percpu_pfn[i] = - alloc_bootmem_pfn(node_percpu[i], goal); - } else if (cpu_isset(i, isolnodes)) { - node_memmap_pfn[i] = alloc_bootmem_pfn(memmap_size, 0); - BUG_ON(node_percpu[i] != 0); + alloc_bootmem_pfn(i, node_percpu[i], + goal); } else { - /* In high PAs, just reserve some pages. */ + /* In non-bootmem zones, just reserve some pages. */ node_memmap_pfn[i] = node_free_pfn[i]; node_free_pfn[i] += PFN_UP(memmap_size); if (!kdata_huge) { @@ -662,16 +712,9 @@ static void __init zone_sizes_init(void) zones_size[ZONE_NORMAL] = end - start; #endif - /* - * Everyone shares node 0's bootmem allocator, but - * we use alloc_remap(), above, to put the actual - * struct page array on the individual controllers, - * which is most of the data that we actually care about. - * We can't place bootmem allocators on the other - * controllers since the bootmem allocator can only - * operate on 32-bit physical addresses. - */ - NODE_DATA(i)->bdata = NODE_DATA(0)->bdata; + /* Take zone metadata from controller 0 if we're isolnode. */ + if (node_isset(i, isolnodes)) + NODE_DATA(i)->bdata = &bootmem_node_data[0]; free_area_init_node(i, zones_size, start, NULL); printk(KERN_DEBUG " Normal zone: %ld per-cpu pages\n", @@ -908,6 +951,15 @@ void __cpuinit setup_cpu(int boot) /* Reset the network state on this cpu. */ reset_network_state(); #endif + +#ifdef CONFIG_HUGETLB_SUPER_PAGES + /* Initialize hugepage support on this cpu. */ + if (!boot) { + int i; + for (i = 0; i < HUGE_SHIFT_ENTRIES; ++i) + hv_set_pte_super_shift(i, huge_shift[i]); + } +#endif } #ifdef CONFIG_BLK_DEV_INITRD diff --git a/arch/tile/kernel/tlb.c b/arch/tile/kernel/tlb.c index a5f241c..3fd54d5 100644 --- a/arch/tile/kernel/tlb.c +++ b/arch/tile/kernel/tlb.c @@ -15,6 +15,7 @@ #include <linux/cpumask.h> #include <linux/module.h> +#include <linux/hugetlb.h> #include <asm/tlbflush.h> #include <asm/homecache.h> #include <hv/hypervisor.h> @@ -49,25 +50,25 @@ void flush_tlb_current_task(void) flush_tlb_mm(current->mm); } -void flush_tlb_page_mm(const struct vm_area_struct *vma, struct mm_struct *mm, +void flush_tlb_page_mm(struct vm_area_struct *vma, struct mm_struct *mm, unsigned long va) { - unsigned long size = hv_page_size(vma); + unsigned long size = vma_kernel_pagesize(vma); int cache = (vma->vm_flags & VM_EXEC) ? HV_FLUSH_EVICT_L1I : 0; flush_remote(0, cache, mm_cpumask(mm), va, size, size, mm_cpumask(mm), NULL, 0); } -void flush_tlb_page(const struct vm_area_struct *vma, unsigned long va) +void flush_tlb_page(struct vm_area_struct *vma, unsigned long va) { flush_tlb_page_mm(vma, vma->vm_mm, va); } EXPORT_SYMBOL(flush_tlb_page); -void flush_tlb_range(const struct vm_area_struct *vma, +void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { - unsigned long size = hv_page_size(vma); + unsigned long size = vma_kernel_pagesize(vma); struct mm_struct *mm = vma->vm_mm; int cache = (vma->vm_flags & VM_EXEC) ? HV_FLUSH_EVICT_L1I : 0; flush_remote(0, cache, mm_cpumask(mm), start, end - start, size, diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index 5d10a74..7cea0fc 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -188,7 +188,7 @@ static pgd_t *get_current_pgd(void) HV_Context ctx = hv_inquire_context(); unsigned long pgd_pfn = ctx.page_table >> PAGE_SHIFT; struct page *pgd_page = pfn_to_page(pgd_pfn); - BUG_ON(PageHighMem(pgd_page)); /* oops, HIGHPTE? */ + BUG_ON(PageHighMem(pgd_page)); return (pgd_t *) __va(ctx.page_table); } diff --git a/arch/tile/mm/homecache.c b/arch/tile/mm/homecache.c index 499f737..dbcbdf7 100644 --- a/arch/tile/mm/homecache.c +++ b/arch/tile/mm/homecache.c @@ -30,6 +30,7 @@ #include <linux/cache.h> #include <linux/smp.h> #include <linux/module.h> +#include <linux/hugetlb.h> #include <asm/page.h> #include <asm/sections.h> diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c index 42cfcba..75716eb 100644 --- a/arch/tile/mm/hugetlbpage.c +++ b/arch/tile/mm/hugetlbpage.c @@ -27,85 +27,145 @@ #include <linux/mman.h> #include <asm/tlb.h> #include <asm/tlbflush.h> +#include <asm/setup.h> + +#ifdef CONFIG_HUGETLB_SUPER_PAGES +/* "Extra" page-size multipliers, one per level of the page table. */ +int huge_shift[HUGE_SHIFT_ENTRIES]; + +/* + * This routine is a hybrid of pte_alloc_map() and pte_alloc_kernel(). + * It assumes that L2 PTEs are never in HIGHMEM (we don't support that). + * It locks the user pagetable, and bumps up the mm->nr_ptes field, + * but otherwise allocate the page table using the kernel versions. + */ +static pte_t *pte_alloc_hugetlb(struct mm_struct *mm, pmd_t *pmd, + unsigned long address) +{ + pte_t *new; + + if (pmd_none(*pmd)) { + new = pte_alloc_one_kernel(mm, address); + if (!new) + return NULL; + + smp_wmb(); /* See comment in __pte_alloc */ + + spin_lock(&mm->page_table_lock); + if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ + mm->nr_ptes++; + pmd_populate_kernel(mm, pmd, new); + new = NULL; + } else + VM_BUG_ON(pmd_trans_splitting(*pmd)); + spin_unlock(&mm->page_table_lock); + if (new) + pte_free_kernel(mm, new); + } + + return pte_offset_kernel(pmd, address); +} +#endif pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz) { pgd_t *pgd; pud_t *pud; - pte_t *pte = NULL; - /* We do not yet support multiple huge page sizes. */ - BUG_ON(sz != PMD_SIZE); + addr &= -sz; /* Mask off any low bits in the address. */ pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); - if (pud) - pte = (pte_t *) pmd_alloc(mm, pud, addr); - BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); - return pte; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + if (sz >= PGDIR_SIZE) { + BUG_ON(sz != PGDIR_SIZE && + sz != PGDIR_SIZE << huge_shift[HUGE_SHIFT_PGDIR]); + return (pte_t *)pud; + } else { + pmd_t *pmd = pmd_alloc(mm, pud, addr); + if (sz >= PMD_SIZE) { + BUG_ON(sz != PMD_SIZE && + sz != (PMD_SIZE << huge_shift[HUGE_SHIFT_PMD])); + return (pte_t *)pmd; + } + else { + if (sz != PAGE_SIZE << huge_shift[HUGE_SHIFT_PAGE]) + panic("Unexpected page size %#lx\n", sz); + return pte_alloc_hugetlb(mm, pmd, addr); + } + } +#else + BUG_ON(sz != PMD_SIZE); + return (pte_t *) pmd_alloc(mm, pud, addr); +#endif } -pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) +static pte_t *get_pte(pte_t *base, int index, int level) { - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd = NULL; - - pgd = pgd_offset(mm, addr); - if (pgd_present(*pgd)) { - pud = pud_offset(pgd, addr); - if (pud_present(*pud)) - pmd = pmd_offset(pud, addr); + pte_t *ptep = base + index; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + if (!pte_present(*ptep) && huge_shift[level] != 0) { + unsigned long mask = -1UL << huge_shift[level]; + pte_t *super_ptep = base + (index & mask); + pte_t pte = *super_ptep; + if (pte_present(pte) && pte_super(pte)) + ptep = super_ptep; } - return (pte_t *) pmd; +#endif + return ptep; } -#ifdef HUGETLB_TEST -struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, - int write) +pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) { - unsigned long start = address; - int length = 1; - int nr; - struct page *page; - struct vm_area_struct *vma; - - vma = find_vma(mm, addr); - if (!vma || !is_vm_hugetlb_page(vma)) - return ERR_PTR(-EINVAL); - - pte = huge_pte_offset(mm, address); - - /* hugetlb should be locked, and hence, prefaulted */ - WARN_ON(!pte || pte_none(*pte)); + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; +#ifdef CONFIG_HUGETLB_SUPER_PAGES + pte_t *pte; +#endif - page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; + /* Get the top-level page table entry. */ + pgd = (pgd_t *)get_pte((pte_t *)mm->pgd, pgd_index(addr), 0); + if (!pgd_present(*pgd)) + return NULL; - WARN_ON(!PageHead(page)); + /* We don't have four levels. */ + pud = pud_offset(pgd, addr); +#ifndef __PAGETABLE_PUD_FOLDED +# error support fourth page table level +#endif - return page; -} + /* Check for an L0 huge PTE, if we have three levels. */ +#ifndef __PAGETABLE_PMD_FOLDED + if (pud_huge(*pud)) + return (pte_t *)pud; -int pmd_huge(pmd_t pmd) -{ - return 0; -} + pmd = (pmd_t *)get_pte((pte_t *)pud_page_vaddr(*pud), + pmd_index(addr), 1); + if (!pmd_present(*pmd)) + return NULL; +#else + pmd = pmd_offset(pud, addr); +#endif -int pud_huge(pud_t pud) -{ - return 0; -} + /* Check for an L1 huge PTE. */ + if (pmd_huge(*pmd)) + return (pte_t *)pmd; + +#ifdef CONFIG_HUGETLB_SUPER_PAGES + /* Check for an L2 huge PTE. */ + pte = get_pte((pte_t *)pmd_page_vaddr(*pmd), pte_index(addr), 2); + if (!pte_present(*pte)) + return NULL; + if (pte_super(*pte)) + return pte; +#endif -struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, - pmd_t *pmd, int write) -{ return NULL; } -#else - struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) { @@ -149,8 +209,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) return 0; } -#endif - #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr, unsigned long len, @@ -323,20 +381,77 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, pgoff, flags); } -static __init int setup_hugepagesz(char *opt) +#ifdef CONFIG_HUGETLB_SUPER_PAGES +static void add_super_size(unsigned long ps, int level, int base_shift) { - unsigned long ps = memparse(opt, &opt); - if (ps == PMD_SIZE) { - hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT); - } else if (ps == PUD_SIZE) { - hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); + int log_ps = __builtin_ctzl(ps); + if ((1UL << log_ps) != ps || (log_ps & 1) != 0) { + pr_warn("Not enabling %ld byte huge pages;" + " must be a power of four.\n", ps); + return; + } + if (log_ps != base_shift) { + if (huge_shift[level] != 0) { + int old_shift = base_shift + huge_shift[level]; + pr_warn("Not enabling %ld MB huge pages;" + " already have size %ld MB.\n", + ps >> 20, (1UL << old_shift) >> 20); + return; + } + if (hv_set_pte_super_shift(level, log_ps - base_shift) != 0) { + pr_warn("Not enabling %ld MB huge pages;" + " no hypervisor support.\n", ps >> 20); + return; + } + printk(KERN_DEBUG "Enabled %ld MB huge pages\n", ps >> 20); + huge_shift[level] = log_ps - base_shift; + } + hugetlb_add_hstate(log_ps - PAGE_SHIFT); +} + +static __init int __setup_hugepagesz(unsigned long ps) +{ + if (ps > 64*1024*1024*1024UL) { + pr_warn("Not enabling %ld MB huge pages;" + " largest legal value is 64 GB .\n", ps >> 20); + } + else if (ps >= PUD_SIZE) { + static long hv_jpage_size; + if (hv_jpage_size == 0) + hv_jpage_size = hv_sysconf(HV_SYSCONF_PAGE_SIZE_JUMBO); + if (hv_jpage_size != PUD_SIZE) { + pr_warn("Not enabling >= %ld MB huge pages:" + " hypervisor reports size %ld\n", + PUD_SIZE >> 20, hv_jpage_size); + } + add_super_size(ps, 0, PUD_SHIFT); + } else if (ps >= PMD_SIZE) { + add_super_size(ps, 1, PMD_SHIFT); + } else if (ps > PAGE_SIZE) { + add_super_size(ps, 2, PAGE_SHIFT); } else { - pr_err("hugepagesz: Unsupported page size %lu M\n", - ps >> 20); - return 0; + pr_err("hugepagesz: Unsupported page size %ld\n", ps); } return 1; } + +bool saw_hugepagesz; + +static __init int setup_hugepagesz(char *opt) +{ + saw_hugepagesz = true; + return __setup_hugepagesz(memparse(opt, NULL)); +} __setup("hugepagesz=", setup_hugepagesz); +/* Provide 1MB size as a standard default if nothing specified. */ +static __init int add_default_hugepagesz(void) +{ + if (!saw_hugepagesz) + __setup_hugepagesz(1 * 1024 * 1024UL); + return 1; +} +arch_initcall(add_default_hugepagesz); +#endif + #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/ diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c index 6119f46..5276f05 100644 --- a/arch/tile/mm/init.c +++ b/arch/tile/mm/init.c @@ -704,6 +704,7 @@ static void __init permanent_kmaps_init(pgd_t *pgd_base) #endif /* CONFIG_HIGHMEM */ +#ifndef CONFIG_64BIT static void __init init_free_pfn_range(unsigned long start, unsigned long end) { unsigned long pfn; @@ -776,6 +777,7 @@ static void __init set_non_bootmem_pages_init(void) init_free_pfn_range(start, end); } } +#endif /* * paging_init() sets up the page tables - note that all of lowmem is @@ -864,8 +866,10 @@ void __init mem_init(void) /* this will put all bootmem onto the freelists */ totalram_pages += free_all_bootmem(); +#ifndef CONFIG_64BIT /* count all remaining LOWMEM and give all HIGHMEM to page allocator */ set_non_bootmem_pages_init(); +#endif codesize = (unsigned long)&_etext - (unsigned long)&_text; datasize = (unsigned long)&_end - (unsigned long)&_sdata; diff --git a/arch/tile/mm/pgtable.c b/arch/tile/mm/pgtable.c index 9c6985f..e52bfc8 100644 --- a/arch/tile/mm/pgtable.c +++ b/arch/tile/mm/pgtable.c @@ -133,15 +133,6 @@ void __set_fixmap(enum fixed_addresses idx, unsigned long phys, pgprot_t flags) set_pte_pfn(address, phys >> PAGE_SHIFT, flags); } -#if defined(CONFIG_HIGHPTE) -pte_t *_pte_offset_map(pmd_t *dir, unsigned long address) -{ - pte_t *pte = kmap_atomic(pmd_page(*dir)) + - (pmd_ptfn(*dir) << HV_LOG2_PAGE_TABLE_ALIGN) & ~PAGE_MASK; - return &pte[pte_index(address)]; -} -#endif - /** * shatter_huge_page() - ensure a given address is mapped by a small page. * @@ -297,10 +288,6 @@ struct page *pgtable_alloc_one(struct mm_struct *mm, unsigned long address, struct page *p; int i; -#ifdef CONFIG_HIGHPTE - flags |= __GFP_HIGHMEM; -#endif - p = alloc_pages(flags, L2_USER_PGTABLE_ORDER); if (p == NULL) return NULL; diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index d9d6c86..a79ff8a 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -301,6 +301,14 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h) #include <asm/hugetlb.h> +#ifndef arch_make_huge_pte +static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, + struct page *page, int writable) +{ + return entry; +} +#endif + static inline struct hstate *page_hstate(struct page *page) { return size_to_hstate(PAGE_SIZE << compound_order(page)); diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a876871..1871753 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2123,6 +2123,7 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, } entry = pte_mkyoung(entry); entry = pte_mkhuge(entry); + entry = arch_make_huge_pte(entry, vma, page, writable); return entry; } -- 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH v3] arch/tile: support multiple huge page sizes dynamically 2012-03-30 19:37 ` [PATCH v3] " Chris Metcalf @ 2012-04-01 12:33 ` Hillf Danton 2012-04-01 16:46 ` Chris Metcalf 0 siblings, 1 reply; 17+ messages in thread From: Hillf Danton @ 2012-04-01 12:33 UTC (permalink / raw) To: Chris Metcalf Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Sat, Mar 31, 2012 at 3:37 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: > This change adds support for a new "super" bit in the PTE, and a > new arch_make_huge_pte() method called from make_huge_pte(). > The Tilera hypervisor sees the bit set at a given level of the page > table and gangs together 4, 16, or 64 consecutive pages from > that level of the hierarchy to create a larger TLB entry. > > One extra "super" page size can be specified at each of the > three levels of the page table hierarchy on tilegx, using the > "hugepagesz" argument on the boot command line. A new hypervisor > API is added to allow Linux to tell the hypervisor how many PTEs > to gang together at each level of the page table. > > To allow pre-allocating huge pages larger than the buddy allocator > can handle, this change modifies the Tilera bootmem support to > put all of memory on tilegx platforms into bootmem. > > As part of this change I eliminate the vestigial CONFIG_HIGHPTE > support, which never worked anyway, and eliminate the hv_page_size() > API in favor of the standard vma_kernel_pagesize() API. > > Reviewed-by: Hillf Danton <dhillf@gmail.com> > Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> > --- > This version of the patch adds a generic no-op definition to > <linux/hugetlb.h> if "arch_make_huge_pte" is not #defined. I'm following > Linus's model in https://lkml.org/lkml/2012/1/19/443 which says you create > the inline, then "#define func func" to indicate that the function exists. > > Hillf, let me know if you want to provide an Acked-by, or I'll leave it > as Reviewed-by. I'm glad you didn't like the v2 patch; > Frankly I like this work, if merged, many tile users benefit. And a few more words, 1, the Reviewed-by tag does not match what I did, really, and over 98% of this work should be reviewed by tile gurus IMO. 2, this work was delivered in a monolithic huge patch, and it is hard to be reviewed. The rule of thumb is to split it into several parts, then reviewers read a good story, chapter after another. 3, I look forward to reading the mm/hugetlb.c chapter. Good weekend -hd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v3] arch/tile: support multiple huge page sizes dynamically 2012-04-01 12:33 ` Hillf Danton @ 2012-04-01 16:46 ` Chris Metcalf 2012-04-02 2:21 ` Hillf Danton 0 siblings, 1 reply; 17+ messages in thread From: Chris Metcalf @ 2012-04-01 16:46 UTC (permalink / raw) To: Hillf Danton Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On 4/1/2012 8:33 AM, Hillf Danton wrote: > On Sat, Mar 31, 2012 at 3:37 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: >> This change adds support for a new "super" bit in the PTE, and a >> new arch_make_huge_pte() method called from make_huge_pte(). >> The Tilera hypervisor sees the bit set at a given level of the page >> table and gangs together 4, 16, or 64 consecutive pages from >> that level of the hierarchy to create a larger TLB entry. >> >> One extra "super" page size can be specified at each of the >> three levels of the page table hierarchy on tilegx, using the >> "hugepagesz" argument on the boot command line. A new hypervisor >> API is added to allow Linux to tell the hypervisor how many PTEs >> to gang together at each level of the page table. >> >> To allow pre-allocating huge pages larger than the buddy allocator >> can handle, this change modifies the Tilera bootmem support to >> put all of memory on tilegx platforms into bootmem. >> >> As part of this change I eliminate the vestigial CONFIG_HIGHPTE >> support, which never worked anyway, and eliminate the hv_page_size() >> API in favor of the standard vma_kernel_pagesize() API. >> >> Reviewed-by: Hillf Danton <dhillf@gmail.com> >> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> >> --- >> This version of the patch adds a generic no-op definition to >> <linux/hugetlb.h> if "arch_make_huge_pte" is not #defined. I'm following >> Linus's model in https://lkml.org/lkml/2012/1/19/443 which says you create >> the inline, then "#define func func" to indicate that the function exists. >> >> Hillf, let me know if you want to provide an Acked-by, or I'll leave it >> as Reviewed-by. I'm glad you didn't like the v2 patch; >> > Frankly I like this work, if merged, many tile users benefit. > > And a few more words, > 1, the Reviewed-by tag does not match what I did, really, and > over 98% of this work should be reviewed by tile gurus IMO. I can split this into two patches, one with your Reviewed-by: (just the include/asm-generic/hugetlb.h and mm/hugetlb.c parts), and one without (the arch/tile stuff). As it happens, I am the tile guru for this code :-) > 2, this work was delivered in a monolithic huge patch, and it is hard > to be reviewed. The rule of thumb is to split it into several parts, then > reviewers read a good story, chapter after another. Yes. I put it all together because it's all inter-dependent; there's no piece of it that's useful in isolation, though as you've observed, there is at least one piece that's helpfully reviewed separately. So does it make sense for me to push the two resulting changes through the tile tree? I'd like to ask Linus to pull this stuff for 3.4 (I know, I'm late in the cycle for that), but obviously it's not much use without the part that you reviewed. I imagine that if I'm pushing it through my tree, it might be more appropriate to have an Acked-by than a Reviewed-by from you, perhaps? What do you think? Thanks! -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v3] arch/tile: support multiple huge page sizes dynamically 2012-04-01 16:46 ` Chris Metcalf @ 2012-04-02 2:21 ` Hillf Danton 0 siblings, 0 replies; 17+ messages in thread From: Hillf Danton @ 2012-04-02 2:21 UTC (permalink / raw) To: Chris Metcalf Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Mon, Apr 2, 2012 at 12:46 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: > > As it happens, I am the tile guru for this code :-) > I see. > > So does it make sense for me to push the two resulting changes through the > tile tree? I'd like to ask Linus to pull this stuff for 3.4 (I know, I'm > late in the cycle for that), but obviously it's not much use without the > part that you reviewed. > No more question:) -hd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-03-31 12:27 ` Hillf Danton 2012-03-30 19:37 ` [PATCH v2] arch/tile: support multiple huge page sizes dynamically Chris Metcalf @ 2012-03-30 20:07 ` Chris Metcalf 2012-04-01 12:10 ` Hillf Danton 1 sibling, 1 reply; 17+ messages in thread From: Chris Metcalf @ 2012-03-30 20:07 UTC (permalink / raw) To: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins, Hillf Danton The race is as follows. Suppose a multi-threaded task forks a new process, thus bumping up the ref count on all the pages. While the fork is occurring (and thus we have marked all the PTEs as read-only), another thread in the original process tries to write to a huge page, taking an access violation from the write-protect and calling hugetlb_cow(). Now, suppose the fork() fails. It will undo the COW and decrement the ref count on the pages, so the ref count on the huge page drops back to 1. Meanwhile hugetlb_cow() also decrements the ref count by one on the original page, since the original address space doesn't need it any more, having copied a new page to replace the original page. This leaves the ref count at zero, and when we call unlock_page(), we panic. The solution is to take an extra reference to the page while we are holding the lock on it. Cc: stable@kernel.org Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> --- This change incorporates Hillf Danton's suggestion to just unconditionally get and put the page around the region of code in question. mm/hugetlb.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1871753..5f53d6b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2701,6 +2701,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, * so no worry about deadlock. */ page = pte_page(entry); + get_page(page); if (page != pagecache_page) lock_page(page); @@ -2732,6 +2733,7 @@ out_page_table_lock: } if (page != pagecache_page) unlock_page(page); + put_page(page); out_mutex: mutex_unlock(&hugetlb_instantiation_mutex); -- 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-03-30 20:07 ` [PATCH v2] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf @ 2012-04-01 12:10 ` Hillf Danton 2012-04-01 16:51 ` Chris Metcalf 0 siblings, 1 reply; 17+ messages in thread From: Hillf Danton @ 2012-04-01 12:10 UTC (permalink / raw) To: Chris Metcalf Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Sat, Mar 31, 2012 at 4:07 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: > The race is as follows. Suppose a multi-threaded task forks a new > process, thus bumping up the ref count on all the pages. While the fork > is occurring (and thus we have marked all the PTEs as read-only), another > thread in the original process tries to write to a huge page, taking an > access violation from the write-protect and calling hugetlb_cow(). Now, > suppose the fork() fails. It will undo the COW and decrement the ref > count on the pages, so the ref count on the huge page drops back to 1. > Meanwhile hugetlb_cow() also decrements the ref count by one on the > original page, since the original address space doesn't need it any more, > having copied a new page to replace the original page. This leaves the > ref count at zero, and when we call unlock_page(), we panic. > > The solution is to take an extra reference to the page while we are > holding the lock on it. > If the following chart matches the above description, === fork on CPU A fault on CPU B ============= ============== ... down_write(&parent->mmap_sem); down_write_nested(&child->mmap_sem); ... while duplicating vmas if error break; ... up_write(&child->mmap_sem); up_write(&parent->mmap_sem); ... down_read(&parent->mmap_sem); ... lock_page(page); handle COW page_mapcount(old_page) == 2 alloc and prepare new_page ... handle error page_remove_rmap(page); put_page(page); ... fold new_page into pte page_remove_rmap(page); put_page(page); ... oops ==> unlock_page(page); up_read(&parent->mmap_sem); === would you please spin with description refreshed? > Cc: stable@kernel.org Let Andrew do the stable work, ok? Best Regards -hd > Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> > --- > This change incorporates Hillf Danton's suggestion to just unconditionally > get and put the page around the region of code in question. > > mm/hugetlb.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 1871753..5f53d6b 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2701,6 +2701,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, > * so no worry about deadlock. > */ > page = pte_page(entry); > + get_page(page); > if (page != pagecache_page) > lock_page(page); > > @@ -2732,6 +2733,7 @@ out_page_table_lock: > } > if (page != pagecache_page) > unlock_page(page); > + put_page(page); > > out_mutex: > mutex_unlock(&hugetlb_instantiation_mutex); > -- > 1.6.5.2 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-01 12:10 ` Hillf Danton @ 2012-04-01 16:51 ` Chris Metcalf 2012-03-30 20:07 ` [PATCH v3] " Chris Metcalf 2012-04-06 22:23 ` [PATCH v2] " Andrew Morton 0 siblings, 2 replies; 17+ messages in thread From: Chris Metcalf @ 2012-04-01 16:51 UTC (permalink / raw) To: Hillf Danton Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On 4/1/2012 8:10 AM, Hillf Danton wrote: > On Sat, Mar 31, 2012 at 4:07 AM, Chris Metcalf <cmetcalf@tilera.com> wrote: >> The race is as follows. Suppose a multi-threaded task forks a new >> process, thus bumping up the ref count on all the pages. While the fork >> is occurring (and thus we have marked all the PTEs as read-only), another >> thread in the original process tries to write to a huge page, taking an >> access violation from the write-protect and calling hugetlb_cow(). Now, >> suppose the fork() fails. It will undo the COW and decrement the ref >> count on the pages, so the ref count on the huge page drops back to 1. >> Meanwhile hugetlb_cow() also decrements the ref count by one on the >> original page, since the original address space doesn't need it any more, >> having copied a new page to replace the original page. This leaves the >> ref count at zero, and when we call unlock_page(), we panic. >> >> The solution is to take an extra reference to the page while we are >> holding the lock on it. >> > If the following chart matches the above description, > > [...] > > would you please spin with description refreshed? Done, and thanks! I added your timeline chart to my description; I figure no harm in having it both ways. >> Cc: stable@kernel.org > Let Andrew do the stable work, ok? Fair point. I'm used to adding the Cc myself for things I push through the arch/tile tree. This of course does make more sense to go through Andrew, so I'll remove it. -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v3] hugetlb: fix race condition in hugetlb_fault() 2012-04-01 16:51 ` Chris Metcalf @ 2012-03-30 20:07 ` Chris Metcalf 2012-04-06 22:23 ` [PATCH v2] " Andrew Morton 1 sibling, 0 replies; 17+ messages in thread From: Chris Metcalf @ 2012-03-30 20:07 UTC (permalink / raw) To: Hillf Danton Cc: linux-kernel, linux-mm, Andrew Morton, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins The race is as follows. Suppose a multi-threaded task forks a new process (on cpu A), thus bumping up the ref count on all the pages. While the fork is occurring (and thus we have marked all the PTEs as read-only), another thread in the original process (on cpu B) tries to write to a huge page, taking an access violation from the write-protect and calling hugetlb_cow(). Now, suppose the fork() fails. It will undo the COW and decrement the ref count on the pages, so the ref count on the huge page drops back to 1. Meanwhile hugetlb_cow() also decrements the ref count by one on the original page, since the original address space doesn't need it any more, having copied a new page to replace the original page. This leaves the ref count at zero, and when we call unlock_page(), we panic. fork on CPU A fault on CPU B ============= ============== ... down_write(&parent->mmap_sem); down_write_nested(&child->mmap_sem); ... while duplicating vmas if error break; ... up_write(&child->mmap_sem); up_write(&parent->mmap_sem); ... down_read(&parent->mmap_sem); ... lock_page(page); handle COW page_mapcount(old_page) == 2 alloc and prepare new_page ... handle error page_remove_rmap(page); put_page(page); ... fold new_page into pte page_remove_rmap(page); put_page(page); ... oops ==> unlock_page(page); up_read(&parent->mmap_sem); The solution is to take an extra reference to the page while we are holding the lock on it. Reviewed-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> --- mm/hugetlb.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1871753..2a04cfd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2701,6 +2701,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, * so no worry about deadlock. */ page = pte_page(entry); + get_page(page); if (page != pagecache_page) lock_page(page); @@ -2732,6 +2733,7 @@ out_page_table_lock: } if (page != pagecache_page) unlock_page(page); + put_page(page); out_mutex: mutex_unlock(&hugetlb_instantiation_mutex); -- 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-01 16:51 ` Chris Metcalf 2012-03-30 20:07 ` [PATCH v3] " Chris Metcalf @ 2012-04-06 22:23 ` Andrew Morton 2012-04-06 23:10 ` Hugh Dickins 1 sibling, 1 reply; 17+ messages in thread From: Andrew Morton @ 2012-04-06 22:23 UTC (permalink / raw) To: Chris Metcalf Cc: Hillf Danton, linux-kernel, linux-mm, Michal Hocko, KAMEZAWA Hiroyuki, Hugh Dickins On Sun, 1 Apr 2012 12:51:49 -0400 Chris Metcalf <cmetcalf@tilera.com> wrote: > >> Cc: stable@kernel.org > > Let Andrew do the stable work, ok? > > Fair point. I'm used to adding the Cc myself for things I push through the > arch/tile tree. This of course does make more sense to go through Andrew, > so I'll remove it. No, please do add the stable tag if you think it is needed. And ensure that the changelog explains why a backport is needed, by describing the user-visible effects of the bug. Tree-owners regularly forget to wonder if a patch should be backported and we end up failing to backport patches which should have been backported. If we have more people flagging backport patches, fewer patches will fall through the cracks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-06 22:23 ` [PATCH v2] " Andrew Morton @ 2012-04-06 23:10 ` Hugh Dickins 2012-04-06 23:26 ` Andrew Morton 0 siblings, 1 reply; 17+ messages in thread From: Hugh Dickins @ 2012-04-06 23:10 UTC (permalink / raw) To: Andrew Morton Cc: Chris Metcalf, Hillf Danton, linux-kernel, linux-mm, Michal Hocko, KAMEZAWA Hiroyuki On Fri, 6 Apr 2012, Andrew Morton wrote: > On Sun, 1 Apr 2012 12:51:49 -0400 > Chris Metcalf <cmetcalf@tilera.com> wrote: > > > >> Cc: stable@kernel.org > > > Let Andrew do the stable work, ok? > > > > Fair point. I'm used to adding the Cc myself for things I push through the > > arch/tile tree. This of course does make more sense to go through Andrew, > > so I'll remove it. > > No, please do add the stable tag if you think it is needed. And ensure > that the changelog explains why a backport is needed, by describing > the user-visible effects of the bug. > > Tree-owners regularly forget to wonder if a patch should be backported > and we end up failing to backport patches which should have been > backported. If we have more people flagging backport patches, fewer > patches will fall through the cracks. The resulting patch is okay; but let's reassure Chris that his original patch was better, before he conceded to make the get_page and put_page unconditional, and added unnecessary detail of the race. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-06 23:10 ` Hugh Dickins @ 2012-04-06 23:26 ` Andrew Morton 2012-04-06 23:35 ` Hugh Dickins 0 siblings, 1 reply; 17+ messages in thread From: Andrew Morton @ 2012-04-06 23:26 UTC (permalink / raw) To: Hugh Dickins Cc: Chris Metcalf, Hillf Danton, linux-kernel, linux-mm, Michal Hocko, KAMEZAWA Hiroyuki On Fri, 6 Apr 2012 16:10:13 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote: > On Fri, 6 Apr 2012, Andrew Morton wrote: > > On Sun, 1 Apr 2012 12:51:49 -0400 > > Chris Metcalf <cmetcalf@tilera.com> wrote: > > > > > >> Cc: stable@kernel.org > > > > Let Andrew do the stable work, ok? > > > > > > Fair point. I'm used to adding the Cc myself for things I push through the > > > arch/tile tree. This of course does make more sense to go through Andrew, > > > so I'll remove it. > > > > No, please do add the stable tag if you think it is needed. And ensure > > that the changelog explains why a backport is needed, by describing > > the user-visible effects of the bug. > > > > Tree-owners regularly forget to wonder if a patch should be backported > > and we end up failing to backport patches which should have been > > backported. If we have more people flagging backport patches, fewer > > patches will fall through the cracks. > > The resulting patch is okay; but let's reassure Chris that his > original patch was better, before he conceded to make the get_page > and put_page unconditional, and added unnecessary detail of the race. > Yes, the v1 patch was better. No reason was given for changing it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-06 23:26 ` Andrew Morton @ 2012-04-06 23:35 ` Hugh Dickins 2012-04-07 0:25 ` Chris Metcalf 0 siblings, 1 reply; 17+ messages in thread From: Hugh Dickins @ 2012-04-06 23:35 UTC (permalink / raw) To: Andrew Morton Cc: Chris Metcalf, Hillf Danton, linux-kernel, linux-mm, Michal Hocko, KAMEZAWA Hiroyuki On Fri, 6 Apr 2012, Andrew Morton wrote: > On Fri, 6 Apr 2012 16:10:13 -0700 (PDT) > Hugh Dickins <hughd@google.com> wrote: > > > > The resulting patch is okay; but let's reassure Chris that his > > original patch was better, before he conceded to make the get_page > > and put_page unconditional, and added unnecessary detail of the race. > > > > Yes, the v1 patch was better. No reason was given for changing it? I think Chris was aiming to be a model citizen, and followed review suggestions that he would actually have done better to resist. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH v2] hugetlb: fix race condition in hugetlb_fault() 2012-04-06 23:35 ` Hugh Dickins @ 2012-04-07 0:25 ` Chris Metcalf 0 siblings, 0 replies; 17+ messages in thread From: Chris Metcalf @ 2012-04-07 0:25 UTC (permalink / raw) To: Hugh Dickins Cc: Andrew Morton, Hillf Danton, linux-kernel, linux-mm, Michal Hocko, KAMEZAWA Hiroyuki On 4/6/2012 7:35 PM, Hugh Dickins wrote: > On Fri, 6 Apr 2012, Andrew Morton wrote: >> On Fri, 6 Apr 2012 16:10:13 -0700 (PDT) >> Hugh Dickins <hughd@google.com> wrote: >>> The resulting patch is okay; but let's reassure Chris that his >>> original patch was better, before he conceded to make the get_page >>> and put_page unconditional, and added unnecessary detail of the race. >>> >> Yes, the v1 patch was better. No reason was given for changing it? > I think Chris was aiming to be a model citizen, and followed review > suggestions that he would actually have done better to resist. Yes, exactly. I figure if I'm submitting patches to mm, I should defer to suggestions from someone like Hillf who has committed a lot more of them than I have. :-) Arguably the unconditional version is simpler at the source code level in any case, and I figure more is usually better when it comes to documenting race conditions, so it didn't seem necessary to push back. Frankly I'm happy to keep my sign-off on either version of the patch and defer to Andrew or whomever as to which one gets taken. -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 17+ messages in thread
end of thread, other threads:[~2012-04-07 0:25 UTC | newest] Thread overview: 17+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-03-30 20:07 [PATCH] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf 2012-03-31 12:27 ` Hillf Danton 2012-03-30 19:37 ` [PATCH v2] arch/tile: support multiple huge page sizes dynamically Chris Metcalf 2012-03-31 14:03 ` Hillf Danton 2012-03-30 19:37 ` [PATCH v3] " Chris Metcalf 2012-04-01 12:33 ` Hillf Danton 2012-04-01 16:46 ` Chris Metcalf 2012-04-02 2:21 ` Hillf Danton 2012-03-30 20:07 ` [PATCH v2] hugetlb: fix race condition in hugetlb_fault() Chris Metcalf 2012-04-01 12:10 ` Hillf Danton 2012-04-01 16:51 ` Chris Metcalf 2012-03-30 20:07 ` [PATCH v3] " Chris Metcalf 2012-04-06 22:23 ` [PATCH v2] " Andrew Morton 2012-04-06 23:10 ` Hugh Dickins 2012-04-06 23:26 ` Andrew Morton 2012-04-06 23:35 ` Hugh Dickins 2012-04-07 0:25 ` Chris Metcalf
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