[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 <hugh@veritas.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 0d4d8bec0df4b4bc94419954fc2471216b710dbb..b44b36e0c29325281daa939d7eeacf8df8d3eb84 100644 (file)
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -285,8 +285,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         * It's fine to use that for setting breakpoints in the vDSO code
         * pages though
         */
-       vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE |
-               VM_MAYEXEC | VM_RESERVED;
+       vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
        vma->vm_flags |= mm->def_flags;
        vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
        vma->vm_ops = &vdso_vmops;

diff --git a/arch/sparc/mm/generic.c b/arch/sparc/mm/generic.c
index 9604893ffdbd020955ec7d0a1e1bbdd6ac942afe..0410bae681f869c6335ab3f8bffd45c14f204920 100644 (file)
--- a/arch/sparc/mm/generic.c
+++ b/arch/sparc/mm/generic.c
@@ -74,7 +74,7 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
        unsigned long offset = GET_PFN(pfn) << PAGE_SHIFT;
 
        /* See comment in mm/memory.c remap_pfn_range */
-       vma->vm_flags |= VM_IO | VM_RESERVED;
+       vma->vm_flags |= VM_IO | VM_RESERVED | VM_UNPAGED;
 
        prot = __pgprot(pg_iobits);
        offset -= from;

diff --git a/arch/sparc64/mm/generic.c b/arch/sparc64/mm/generic.c
index 112c316e7cd213e6b59cc1284a49d7fc05aae898..8fd4cb1f050a19e394068abce75e8ff08fbd57e7 100644 (file)
--- a/arch/sparc64/mm/generic.c
+++ b/arch/sparc64/mm/generic.c
@@ -128,7 +128,7 @@ int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
        unsigned long offset = GET_PFN(pfn) << PAGE_SHIFT;
 
        /* See comment in mm/memory.c remap_pfn_range */
-       vma->vm_flags |= VM_IO | VM_RESERVED;
+       vma->vm_flags |= VM_IO | VM_RESERVED | VM_UNPAGED;
 
        prot = __pgprot(pg_iobits);
        offset -= from;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9701210c66805d76fdb368e3424379c80f9b22c6..f0cdfd18db55b7edfe3af313dbf4cd9bcca22f70 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -144,7 +144,8 @@ extern unsigned int kobjsize(const void *objp);
 
 #define VM_GROWSDOWN   0x00000100      /* general info on the segment */
 #define VM_GROWSUP     0x00000200
-#define VM_SHM         0x00000400      /* shared memory area, don't swap out */
+#define VM_SHM         0x00000000      /* Means nothing: delete it later */
+#define VM_UNPAGED     0x00000400      /* Pages managed without map count */
 #define VM_DENYWRITE   0x00000800      /* ETXTBSY on write attempts.. */
 
 #define VM_EXECUTABLE  0x00001000
@@ -157,7 +158,7 @@ extern unsigned int kobjsize(const void *objp);
 
 #define VM_DONTCOPY    0x00020000      /* Do not copy this vma on fork */
 #define VM_DONTEXPAND  0x00040000      /* Cannot expand with mremap() */
-#define VM_RESERVED    0x00080000      /* Pages managed in a special way */
+#define VM_RESERVED    0x00080000      /* Count as reserved_vm like IO */
 #define VM_ACCOUNT     0x00100000      /* Is a VM accounted object */
 #define VM_HUGETLB     0x00400000      /* Huge TLB Page VM */
 #define VM_NONLINEAR   0x00800000      /* Is non-linear (remap_file_pages) */

diff --git a/mm/fremap.c b/mm/fremap.c
index d862be3bc3e31f6d1914995b6bc2a6d5fa75e180..94254c5d7a18cf40f64dfe32ec4fdde41a1e9aae 100644 (file)
--- 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 17aaf3e1644983a5a4fac14bef8f009f71fe866c..328a3bcce5271ee969e231962354159227da9eba 100644 (file)
--- 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 cfce5f1f30f20b36bc8a41ebc430bfecf7d9608d..ece04963158e4c61cb89c0bd38736d2dc59f76d1 100644 (file)
--- 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 5abc57c2b8bdd3804708267832fd20d29a65be71..5609a31bdf229e51300474764c320d0404767fe5 100644 (file)
--- 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 0e040e9c39d835a7cf938468be6a9b7bccb95c2d..b3f4caf3010b3ae998e456ba99faeff335623e07 100644 (file)
--- 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);