From 0b14c179a483e71ea41df2aa4a661760063115bd Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 21 Nov 2005 21:32:15 -0800 Subject: [PATCH] unpaged: VM_UNPAGED Although we tend to associate VM_RESERVED with remap_pfn_range, quite a few drivers set VM_RESERVED on areas which are then populated by nopage. The PageReserved removal in 2.6.15-rc1 changed VM_RESERVED not to free pages in zap_pte_range, without changing those drivers not to set it: so their pages just leak away. Let's not change miscellaneous drivers now: introduce VM_UNPAGED at the core, to flag the special areas where the ptes may have no struct page, or if they have then it's not to be touched. Replace most instances of VM_RESERVED in core mm by VM_UNPAGED. Force it on in remap_pfn_range, and the sparc and sparc64 io_remap_pfn_range. Revert addition of VM_RESERVED to powerpc vdso, it's not needed there. Is it needed anywhere? It still governs the mm->reserved_vm statistic, and special vmas not to be merged, and areas not to be core dumped; but could probably be eliminated later (the drivers are probably specifying it because in 2.4 it kept swapout off the vma, but in 2.6 we work from the LRU, which these pages don't get on). Use the VM_SHM slot for VM_UNPAGED, and define VM_SHM to 0: it serves no purpose whatsoever, and should be removed from drivers when we clean up. Signed-off-by: Hugh Dickins Acked-by: William Irwin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/fremap.c | 4 ++-- mm/madvise.c | 2 +- mm/memory.c | 30 ++++++++++++++++++------------ mm/mempolicy.c | 2 +- mm/msync.c | 4 ++-- 5 files changed, 24 insertions(+), 18 deletions(-) (limited to 'mm') diff --git a/mm/fremap.c b/mm/fremap.c index d862be3bc3e..94254c5d7a1 100644 --- a/mm/fremap.c +++ b/mm/fremap.c @@ -65,7 +65,7 @@ int install_page(struct mm_struct *mm, struct vm_area_struct *vma, pte_t pte_val; spinlock_t *ptl; - BUG_ON(vma->vm_flags & VM_RESERVED); + BUG_ON(vma->vm_flags & VM_UNPAGED); pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); @@ -122,7 +122,7 @@ int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, pte_t pte_val; spinlock_t *ptl; - BUG_ON(vma->vm_flags & VM_RESERVED); + BUG_ON(vma->vm_flags & VM_UNPAGED); pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); diff --git a/mm/madvise.c b/mm/madvise.c index 17aaf3e1644..328a3bcce52 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -126,7 +126,7 @@ static long madvise_dontneed(struct vm_area_struct * vma, unsigned long start, unsigned long end) { *prev = vma; - if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_RESERVED)) + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_UNPAGED)) return -EINVAL; if (unlikely(vma->vm_flags & VM_NONLINEAR)) { diff --git a/mm/memory.c b/mm/memory.c index cfce5f1f30f..ece04963158 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -334,7 +334,7 @@ static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) /* * This function is called to print an error when a pte in a - * !VM_RESERVED region is found pointing to an invalid pfn (which + * !VM_UNPAGED region is found pointing to an invalid pfn (which * is an error. * * The calling function must still handle the error. @@ -381,15 +381,15 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, goto out_set_pte; } - /* If the region is VM_RESERVED, the mapping is not + /* If the region is VM_UNPAGED, the mapping is not * mapped via rmap - duplicate the pte as is. */ - if (vm_flags & VM_RESERVED) + if (vm_flags & VM_UNPAGED) goto out_set_pte; pfn = pte_pfn(pte); /* If the pte points outside of valid memory but - * the region is not VM_RESERVED, we have a problem. + * the region is not VM_UNPAGED, we have a problem. */ if (unlikely(!pfn_valid(pfn))) { print_bad_pte(vma, pte, addr); @@ -528,7 +528,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, * readonly mappings. The tradeoff is that copy_page_range is more * efficient than faulting. */ - if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) { + if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_UNPAGED))) { if (!vma->anon_vma) return 0; } @@ -572,7 +572,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, (*zap_work) -= PAGE_SIZE; - if (!(vma->vm_flags & VM_RESERVED)) { + if (!(vma->vm_flags & VM_UNPAGED)) { unsigned long pfn = pte_pfn(ptent); if (unlikely(!pfn_valid(pfn))) print_bad_pte(vma, ptent, addr); @@ -1191,10 +1191,16 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, * rest of the world about it: * VM_IO tells people not to look at these pages * (accesses can have side effects). - * VM_RESERVED tells the core MM not to "manage" these pages - * (e.g. refcount, mapcount, try to swap them out). + * VM_RESERVED is specified all over the place, because + * in 2.4 it kept swapout's vma scan off this vma; but + * in 2.6 the LRU scan won't even find its pages, so this + * flag means no more than count its pages in reserved_vm, + * and omit it from core dump, even when VM_IO turned off. + * VM_UNPAGED tells the core MM not to "manage" these pages + * (e.g. refcount, mapcount, try to swap them out): in + * particular, zap_pte_range does not try to free them. */ - vma->vm_flags |= VM_IO | VM_RESERVED; + vma->vm_flags |= VM_IO | VM_RESERVED | VM_UNPAGED; BUG_ON(addr >= end); pfn -= addr >> PAGE_SHIFT; @@ -1276,7 +1282,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, pte_t entry; int ret = VM_FAULT_MINOR; - BUG_ON(vma->vm_flags & VM_RESERVED); + BUG_ON(vma->vm_flags & VM_UNPAGED); if (unlikely(!pfn_valid(pfn))) { /* @@ -1924,7 +1930,7 @@ retry: inc_mm_counter(mm, anon_rss); lru_cache_add_active(new_page); page_add_anon_rmap(new_page, vma, address); - } else if (!(vma->vm_flags & VM_RESERVED)) { + } else if (!(vma->vm_flags & VM_UNPAGED)) { inc_mm_counter(mm, file_rss); page_add_file_rmap(new_page); } @@ -2203,7 +2209,7 @@ static int __init gate_vma_init(void) gate_vma.vm_start = FIXADDR_USER_START; gate_vma.vm_end = FIXADDR_USER_END; gate_vma.vm_page_prot = PAGE_READONLY; - gate_vma.vm_flags = VM_RESERVED; + gate_vma.vm_flags = 0; return 0; } __initcall(gate_vma_init); diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 5abc57c2b8b..5609a31bdf2 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -269,7 +269,7 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end, first = find_vma(mm, start); if (!first) return ERR_PTR(-EFAULT); - if (first->vm_flags & VM_RESERVED) + if (first->vm_flags & VM_UNPAGED) return ERR_PTR(-EACCES); prev = NULL; for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) { diff --git a/mm/msync.c b/mm/msync.c index 0e040e9c39d..b3f4caf3010 100644 --- a/mm/msync.c +++ b/mm/msync.c @@ -97,9 +97,9 @@ static void msync_page_range(struct vm_area_struct *vma, /* For hugepages we can't go walking the page table normally, * but that's ok, hugetlbfs is memory based, so we don't need * to do anything more on an msync(). - * Can't do anything with VM_RESERVED regions either. + * Can't do anything with VM_UNPAGED regions either. */ - if (vma->vm_flags & (VM_HUGETLB|VM_RESERVED)) + if (vma->vm_flags & (VM_HUGETLB|VM_UNPAGED)) return; BUG_ON(addr >= end); -- cgit v1.2.3-18-g5258