From 872fec16d9a0ed3b75b8893aa217e49cca575ee5 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sat, 29 Oct 2005 18:16:21 -0700 Subject: [PATCH] mm: init_mm without ptlock First step in pushing down the page_table_lock. init_mm.page_table_lock has been used throughout the architectures (usually for ioremap): not to serialize kernel address space allocation (that's usually vmlist_lock), but because pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it. Reverse that: don't lock or unlock init_mm.page_table_lock in any of the architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take and drop it when allocating a new one, to check lest a racing task already did. Similarly no page_table_lock in vmalloc's map_vm_area. Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle user mms, which are converted only by a later patch, for now they have to lock differently according to whether or not it's init_mm. If sources get muddled, there's a danger that an arch source taking init_mm.page_table_lock will be mixed with common source also taking it (or neither take it). So break the rules and make another change, which should break the build for such a mismatch: remove the redundant mm arg from pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13). Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64 used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64 map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free took page_table_lock for no good reason. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'mm/vmalloc.c') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 5e9120598799..54a90e83cb31 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -89,7 +89,7 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, { pte_t *pte; - pte = pte_alloc_kernel(&init_mm, pmd, addr); + pte = pte_alloc_kernel(pmd, addr); if (!pte) return -ENOMEM; do { @@ -147,14 +147,12 @@ int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages) BUG_ON(addr >= end); pgd = pgd_offset_k(addr); - spin_lock(&init_mm.page_table_lock); do { next = pgd_addr_end(addr, end); err = vmap_pud_range(pgd, addr, next, prot, pages); if (err) break; } while (pgd++, addr = next, addr != end); - spin_unlock(&init_mm.page_table_lock); flush_cache_vmap((unsigned long) area->addr, end); return err; } -- cgit v1.2.3-55-g7522