Make mmu_gather preemptible by using a small on stack list and use an option allocation to speed things up. Preemptible mmu_gather is desired in general and usable once i_mmap_lock becomes a mutex. Doing it before the mutex conversion saves us from having to rework the code by moving the mmu_gather bits inside the i_mmap_lock. Cc: Benjamin Herrenschmidt Cc: David Miller Cc: Martin Schwidefsky Cc: Russell King Cc: Paul Mundt Cc: Jeff Dike Cc: Tony Luck Signed-off-by: Peter Zijlstra --- fs/exec.c | 10 ++++----- include/asm-generic/tlb.h | 51 +++++++++++++++++++++++++++++----------------- include/linux/mm.h | 2 - mm/memory.c | 27 +++++------------------- mm/mmap.c | 16 +++++++------- 5 files changed, 53 insertions(+), 53 deletions(-) Index: linux-2.6/fs/exec.c =================================================================== --- linux-2.6.orig/fs/exec.c +++ linux-2.6/fs/exec.c @@ -504,7 +504,7 @@ static int shift_arg_pages(struct vm_are unsigned long length = old_end - old_start; unsigned long new_start = old_start - shift; unsigned long new_end = old_end - shift; - struct mmu_gather *tlb; + struct mmu_gather tlb; BUG_ON(new_start > new_end); @@ -530,12 +530,12 @@ static int shift_arg_pages(struct vm_are return -ENOMEM; lru_add_drain(); - tlb = tlb_gather_mmu(mm, 0); + tlb_gather_mmu(&tlb, mm, 0); if (new_end > old_start) { /* * when the old and new regions overlap clear from new_end. */ - free_pgd_range(tlb, new_end, old_end, new_end, + free_pgd_range(&tlb, new_end, old_end, new_end, vma->vm_next ? vma->vm_next->vm_start : 0); } else { /* @@ -544,10 +544,10 @@ static int shift_arg_pages(struct vm_are * have constraints on va-space that make this illegal (IA64) - * for the others its just a little faster. */ - free_pgd_range(tlb, old_start, old_end, new_end, + free_pgd_range(&tlb, old_start, old_end, new_end, vma->vm_next ? vma->vm_next->vm_start : 0); } - tlb_finish_mmu(tlb, new_end, old_end); + tlb_finish_mmu(&tlb, new_end, old_end); /* * Shrink the vma to just the new range. Always succeeds. Index: linux-2.6/include/asm-generic/tlb.h =================================================================== --- linux-2.6.orig/include/asm-generic/tlb.h +++ linux-2.6/include/asm-generic/tlb.h @@ -22,14 +22,8 @@ * and page free order so much.. */ #ifdef CONFIG_SMP - #ifdef ARCH_FREE_PTR_NR - #define FREE_PTR_NR ARCH_FREE_PTR_NR - #else - #define FREE_PTE_NR 506 - #endif #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) #else - #define FREE_PTE_NR 1 #define tlb_fast_mode(tlb) 1 #endif @@ -39,30 +33,48 @@ struct mmu_gather { struct mm_struct *mm; unsigned int nr; /* set to ~0U means fast mode */ + unsigned int max; /* nr < max */ unsigned int need_flush;/* Really unmapped some ptes? */ unsigned int fullmm; /* non-zero means full mm flush */ - struct page * pages[FREE_PTE_NR]; +#ifdef HAVE_ARCH_MMU_GATHER + struct arch_mmu_gather arch; +#endif + struct page **pages; + struct page *local[8]; }; -/* Users of the generic TLB shootdown code must declare this storage space. */ -DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); +static inline void __tlb_alloc_pages(struct mmu_gather *tlb) +{ + unsigned long addr = __get_free_pages(GFP_ATOMIC, 0); + + if (addr) { + tlb->pages = (void *)addr; + tlb->max = PAGE_SIZE / sizeof(struct page *); + } +} /* tlb_gather_mmu * Return a pointer to an initialized struct mmu_gather. */ -static inline struct mmu_gather * -tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) +static inline void +tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush) { - struct mmu_gather *tlb = &get_cpu_var(mmu_gathers); - tlb->mm = mm; - /* Use fast mode if only one CPU is online */ - tlb->nr = num_online_cpus() > 1 ? 0U : ~0U; + tlb->max = ARRAY_SIZE(tlb->local); + tlb->pages = tlb->local; + + if (num_online_cpus() > 1) { + tlb->nr = 0; + __tlb_alloc_pages(tlb); + } else /* Use fast mode if only one CPU is online */ + tlb->nr = ~0U; tlb->fullmm = full_mm_flush; - return tlb; +#ifdef HAVE_ARCH_MMU_GATHER + tlb->arch = ARCH_MMU_GATHER_INIT; +#endif } static inline void @@ -75,6 +87,8 @@ tlb_flush_mmu(struct mmu_gather *tlb, un if (!tlb_fast_mode(tlb)) { free_pages_and_swap_cache(tlb->pages, tlb->nr); tlb->nr = 0; + if (tlb->pages == tlb->local) + __tlb_alloc_pages(tlb); } } @@ -90,7 +104,8 @@ tlb_finish_mmu(struct mmu_gather *tlb, u /* keep the page table cache within bounds */ check_pgt_cache(); - put_cpu_var(mmu_gathers); + if (tlb->pages != tlb->local) + free_pages((unsigned long)tlb->pages, 0); } /* tlb_remove_page @@ -106,7 +121,7 @@ static inline void tlb_remove_page(struc return; } tlb->pages[tlb->nr++] = page; - if (tlb->nr >= FREE_PTE_NR) + if (tlb->nr >= tlb->max) tlb_flush_mmu(tlb, 0, 0); } Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h +++ linux-2.6/include/linux/mm.h @@ -769,7 +769,7 @@ int zap_vma_ptes(struct vm_area_struct * unsigned long size); unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned long size, struct zap_details *); -unsigned long unmap_vmas(struct mmu_gather **tlb, +unsigned long unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma, unsigned long start_addr, unsigned long end_addr, unsigned long *nr_accounted, struct zap_details *); Index: linux-2.6/mm/memory.c =================================================================== --- linux-2.6.orig/mm/memory.c +++ linux-2.6/mm/memory.c @@ -1093,17 +1093,14 @@ static unsigned long unmap_page_range(st * ensure that any thus-far unmapped pages are flushed before unmap_vmas() * drops the lock and schedules. */ -unsigned long unmap_vmas(struct mmu_gather **tlbp, +unsigned long unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start_addr, unsigned long end_addr, unsigned long *nr_accounted, struct zap_details *details) { long zap_work = ZAP_BLOCK_SIZE; - unsigned long tlb_start = 0; /* For tlb_finish_mmu */ - int tlb_start_valid = 0; unsigned long start = start_addr; spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; - int fullmm = (*tlbp)->fullmm; struct mm_struct *mm = vma->vm_mm; mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); @@ -1124,11 +1121,6 @@ unsigned long unmap_vmas(struct mmu_gath untrack_pfn_vma(vma, 0, 0); while (start != end) { - if (!tlb_start_valid) { - tlb_start = start; - tlb_start_valid = 1; - } - if (unlikely(is_vm_hugetlb_page(vma))) { /* * It is undesirable to test vma->vm_file as it @@ -1149,7 +1141,7 @@ unsigned long unmap_vmas(struct mmu_gath start = end; } else - start = unmap_page_range(*tlbp, vma, + start = unmap_page_range(tlb, vma, start, end, &zap_work, details); if (zap_work > 0) { @@ -1157,19 +1149,13 @@ unsigned long unmap_vmas(struct mmu_gath break; } - tlb_finish_mmu(*tlbp, tlb_start, start); - if (need_resched() || (i_mmap_lock && spin_needbreak(i_mmap_lock))) { - if (i_mmap_lock) { - *tlbp = NULL; + if (i_mmap_lock) goto out; - } cond_resched(); } - *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); - tlb_start_valid = 0; zap_work = ZAP_BLOCK_SIZE; } } @@ -1189,16 +1175,15 @@ unsigned long zap_page_range(struct vm_a unsigned long size, struct zap_details *details) { struct mm_struct *mm = vma->vm_mm; - struct mmu_gather *tlb; + struct mmu_gather tlb; unsigned long end = address + size; unsigned long nr_accounted = 0; lru_add_drain(); - tlb = tlb_gather_mmu(mm, 0); + tlb_gather_mmu(&tlb, mm, 0); update_hiwater_rss(mm); end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); - if (tlb) - tlb_finish_mmu(tlb, address, end); + tlb_finish_mmu(&tlb, address, end); return end; } Index: linux-2.6/mm/mmap.c =================================================================== --- linux-2.6.orig/mm/mmap.c +++ linux-2.6/mm/mmap.c @@ -1896,17 +1896,17 @@ static void unmap_region(struct mm_struc unsigned long start, unsigned long end) { struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; - struct mmu_gather *tlb; + struct mmu_gather tlb; unsigned long nr_accounted = 0; lru_add_drain(); - tlb = tlb_gather_mmu(mm, 0); + tlb_gather_mmu(&tlb, mm, 0); update_hiwater_rss(mm); unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); - free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, + free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, next? next->vm_start: 0); - tlb_finish_mmu(tlb, start, end); + tlb_finish_mmu(&tlb, start, end); } /* @@ -2247,7 +2247,7 @@ EXPORT_SYMBOL(do_brk); /* Release all mmaps. */ void exit_mmap(struct mm_struct *mm) { - struct mmu_gather *tlb; + struct mmu_gather tlb; struct vm_area_struct *vma; unsigned long nr_accounted = 0; unsigned long end; @@ -2272,14 +2272,14 @@ void exit_mmap(struct mm_struct *mm) lru_add_drain(); flush_cache_mm(mm); - tlb = tlb_gather_mmu(mm, 1); + tlb_gather_mmu(&tlb, mm, 1); /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use -1 here to ensure all VMAs in the mm are unmapped */ end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); vm_unacct_memory(nr_accounted); - free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); - tlb_finish_mmu(tlb, 0, end); + free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); + tlb_finish_mmu(&tlb, 0, end); /* * Walk the list again, actually closing and freeing it, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/