--- /dev/null
+/*
+ * linux/arch/i386/mm/pgtable.c
+ */
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/fixmap.h>
+#include <asm/e820.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+#include <asm/mmu_context.h>
+
+#include <xen/features.h>
+#include <xen/foreign_page.h>
+#include <asm/hypervisor.h>
+
+static void pgd_test_and_unpin(pgd_t *pgd);
+
+void show_mem(void)
+{
+ int total = 0, reserved = 0;
+ int shared = 0, cached = 0;
+ int highmem = 0;
+ struct page *page;
+ pg_data_t *pgdat;
+ unsigned long i;
+ struct page_state ps;
+ unsigned long flags;
+
+ printk(KERN_INFO "Mem-info:\n");
+ show_free_areas();
+ printk(KERN_INFO "Free swap: %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
+ for_each_online_pgdat(pgdat) {
+ pgdat_resize_lock(pgdat, &flags);
+ for (i = 0; i < pgdat->node_spanned_pages; ++i) {
+ page = pgdat_page_nr(pgdat, i);
+ total++;
+ if (PageHighMem(page))
+ highmem++;
+ if (PageReserved(page))
+ reserved++;
+ else if (PageSwapCache(page))
+ cached++;
+ else if (page_count(page))
+ shared += page_count(page) - 1;
+ }
+ pgdat_resize_unlock(pgdat, &flags);
+ }
+ printk(KERN_INFO "%d pages of RAM\n", total);
+ printk(KERN_INFO "%d pages of HIGHMEM\n", highmem);
+ printk(KERN_INFO "%d reserved pages\n", reserved);
+ printk(KERN_INFO "%d pages shared\n", shared);
+ printk(KERN_INFO "%d pages swap cached\n", cached);
+
+ get_page_state(&ps);
+ printk(KERN_INFO "%lu pages dirty\n", ps.nr_dirty);
+ printk(KERN_INFO "%lu pages writeback\n", ps.nr_writeback);
+ printk(KERN_INFO "%lu pages mapped\n", ps.nr_mapped);
+ printk(KERN_INFO "%lu pages slab\n", ps.nr_slab);
+ printk(KERN_INFO "%lu pages pagetables\n", ps.nr_page_table_pages);
+}
+
+/*
+ * Associate a virtual page frame with a given physical page frame
+ * and protection flags for that frame.
+ */
+static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = swapper_pg_dir + pgd_index(vaddr);
+ if (pgd_none(*pgd)) {
+ BUG();
+ return;
+ }
+ pud = pud_offset(pgd, vaddr);
+ if (pud_none(*pud)) {
+ BUG();
+ return;
+ }
+ pmd = pmd_offset(pud, vaddr);
+ if (pmd_none(*pmd)) {
+ BUG();
+ return;
+ }
+ pte = pte_offset_kernel(pmd, vaddr);
+ /* <pfn,flags> stored as-is, to permit clearing entries */
+ set_pte(pte, pfn_pte(pfn, flags));
+
+ /*
+ * It's enough to flush this one mapping.
+ * (PGE mappings get flushed as well)
+ */
+ __flush_tlb_one(vaddr);
+}
+
+/*
+ * Associate a virtual page frame with a given physical page frame
+ * and protection flags for that frame.
+ */
+static void set_pte_pfn_ma(unsigned long vaddr, unsigned long pfn,
+ pgprot_t flags)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pgd = swapper_pg_dir + pgd_index(vaddr);
+ if (pgd_none(*pgd)) {
+ BUG();
+ return;
+ }
+ pud = pud_offset(pgd, vaddr);
+ if (pud_none(*pud)) {
+ BUG();
+ return;
+ }
+ pmd = pmd_offset(pud, vaddr);
+ if (pmd_none(*pmd)) {
+ BUG();
+ return;
+ }
+ pte = pte_offset_kernel(pmd, vaddr);
+ /* <pfn,flags> stored as-is, to permit clearing entries */
+ set_pte(pte, pfn_pte_ma(pfn, flags));
+
+ /*
+ * It's enough to flush this one mapping.
+ * (PGE mappings get flushed as well)
+ */
+ __flush_tlb_one(vaddr);
+}
+
+/*
+ * Associate a large virtual page frame with a given physical page frame
+ * and protection flags for that frame. pfn is for the base of the page,
+ * vaddr is what the page gets mapped to - both must be properly aligned.
+ * The pmd must already be instantiated. Assumes PAE mode.
+ */
+void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ if (vaddr & (PMD_SIZE-1)) { /* vaddr is misaligned */
+ printk(KERN_WARNING "set_pmd_pfn: vaddr misaligned\n");
+ return; /* BUG(); */
+ }
+ if (pfn & (PTRS_PER_PTE-1)) { /* pfn is misaligned */
+ printk(KERN_WARNING "set_pmd_pfn: pfn misaligned\n");
+ return; /* BUG(); */
+ }
+ pgd = swapper_pg_dir + pgd_index(vaddr);
+ if (pgd_none(*pgd)) {
+ printk(KERN_WARNING "set_pmd_pfn: pgd_none\n");
+ return; /* BUG(); */
+ }
+ pud = pud_offset(pgd, vaddr);
+ pmd = pmd_offset(pud, vaddr);
+ set_pmd(pmd, pfn_pmd(pfn, flags));
+ /*
+ * It's enough to flush this one mapping.
+ * (PGE mappings get flushed as well)
+ */
+ __flush_tlb_one(vaddr);
+}
+
+static int nr_fixmaps = 0;
+unsigned long __FIXADDR_TOP = (HYPERVISOR_VIRT_START - 2 * PAGE_SIZE);
+EXPORT_SYMBOL(__FIXADDR_TOP);
+
+void __set_fixmap (enum fixed_addresses idx, maddr_t phys, pgprot_t flags)
+{
+ unsigned long address = __fix_to_virt(idx);
+
+ if (idx >= __end_of_fixed_addresses) {
+ BUG();
+ return;
+ }
+ switch (idx) {
+ case FIX_WP_TEST:
+ case FIX_VSYSCALL:
+#ifdef CONFIG_X86_F00F_BUG
+ case FIX_F00F_IDT:
+#endif
+ set_pte_pfn(address, phys >> PAGE_SHIFT, flags);
+ break;
+ default:
+ set_pte_pfn_ma(address, phys >> PAGE_SHIFT, flags);
+ break;
+ }
+ nr_fixmaps++;
+}
+
+void set_fixaddr_top(unsigned long top)
+{
+ BUG_ON(nr_fixmaps > 0);
+ __FIXADDR_TOP = top - PAGE_SIZE;
+}
+
+pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
+{
+ pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
+ if (pte)
+ make_lowmem_page_readonly(pte, XENFEAT_writable_page_tables);
+ return pte;
+}
+
+struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
+{
+ struct page *pte;
+
+#ifdef CONFIG_HIGHPTE
+ pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
+#else
+ pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
+ if (pte) {
+ SetPageForeign(pte, pte_free);
+ init_page_count(pte);
+ }
+#endif
+ return pte;
+}
+
+void pte_free(struct page *pte)
+{
+ unsigned long va = (unsigned long)__va(page_to_pfn(pte)<<PAGE_SHIFT);
+
+ if (!pte_write(*virt_to_ptep(va)))
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ va, pfn_pte(page_to_pfn(pte), PAGE_KERNEL), 0));
+
+ ClearPageForeign(pte);
+ init_page_count(pte);
+
+ __free_page(pte);
+}
+
+void pmd_ctor(void *pmd, kmem_cache_t *cache, unsigned long flags)
+{
+ memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
+}
+
+/*
+ * List of all pgd's needed for non-PAE so it can invalidate entries
+ * in both cached and uncached pgd's; not needed for PAE since the
+ * kernel pmd is shared. If PAE were not to share the pmd a similar
+ * tactic would be needed. This is essentially codepath-based locking
+ * against pageattr.c; it is the unique case in which a valid change
+ * of kernel pagetables can't be lazily synchronized by vmalloc faults.
+ * vmalloc faults work because attached pagetables are never freed.
+ * The locking scheme was chosen on the basis of manfred's
+ * recommendations and having no core impact whatsoever.
+ * -- wli
+ */
+DEFINE_SPINLOCK(pgd_lock);
+struct page *pgd_list;
+
+static inline void pgd_list_add(pgd_t *pgd)
+{
+ struct page *page = virt_to_page(pgd);
+ page->index = (unsigned long)pgd_list;
+ if (pgd_list)
+ set_page_private(pgd_list, (unsigned long)&page->index);
+ pgd_list = page;
+ set_page_private(page, (unsigned long)&pgd_list);
+}
+
+static inline void pgd_list_del(pgd_t *pgd)
+{
+ struct page *next, **pprev, *page = virt_to_page(pgd);
+ next = (struct page *)page->index;
+ pprev = (struct page **)page_private(page);
+ *pprev = next;
+ if (next)
+ set_page_private(next, (unsigned long)pprev);
+}
+
+void pgd_ctor(void *pgd, kmem_cache_t *cache, unsigned long unused)
+{
+ unsigned long flags;
+
+ if (PTRS_PER_PMD > 1) {
+ if (HAVE_SHARED_KERNEL_PMD)
+ clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
+ swapper_pg_dir + USER_PTRS_PER_PGD,
+ KERNEL_PGD_PTRS);
+ } else {
+ spin_lock_irqsave(&pgd_lock, flags);
+ clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
+ swapper_pg_dir + USER_PTRS_PER_PGD,
+ KERNEL_PGD_PTRS);
+ memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
+ pgd_list_add(pgd);
+ spin_unlock_irqrestore(&pgd_lock, flags);
+ }
+}
+
+/* never called when PTRS_PER_PMD > 1 */
+void pgd_dtor(void *pgd, kmem_cache_t *cache, unsigned long unused)
+{
+ unsigned long flags; /* can be called from interrupt context */
+
+ spin_lock_irqsave(&pgd_lock, flags);
+ pgd_list_del(pgd);
+ spin_unlock_irqrestore(&pgd_lock, flags);
+
+ pgd_test_and_unpin(pgd);
+}
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+ int i;
+ pgd_t *pgd = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
+ pmd_t **pmd;
+ unsigned long flags;
+
+ pgd_test_and_unpin(pgd);
+
+ if (PTRS_PER_PMD == 1 || !pgd)
+ return pgd;
+
+ if (HAVE_SHARED_KERNEL_PMD) {
+ for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
+ pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
+ if (!pmd)
+ goto out_oom;
+ set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
+ }
+ return pgd;
+ }
+
+ /*
+ * We can race save/restore (if we sleep during a GFP_KERNEL memory
+ * allocation). We therefore store virtual addresses of pmds as they
+ * do not change across save/restore, and poke the machine addresses
+ * into the pgdir under the pgd_lock.
+ */
+ pmd = kmalloc(PTRS_PER_PGD * sizeof(pmd_t *), GFP_KERNEL);
+ if (!pmd) {
+ kmem_cache_free(pgd_cache, pgd);
+ return NULL;
+ }
+
+ /* Allocate pmds, remember virtual addresses. */
+ for (i = 0; i < PTRS_PER_PGD; ++i) {
+ pmd[i] = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
+ if (!pmd[i])
+ goto out_oom;
+ }
+
+ spin_lock_irqsave(&pgd_lock, flags);
+
+ /* Protect against save/restore: move below 4GB under pgd_lock. */
+ if (!xen_feature(XENFEAT_pae_pgdir_above_4gb)) {
+ int rc = xen_create_contiguous_region(
+ (unsigned long)pgd, 0, 32);
+ if (rc) {
+ spin_unlock_irqrestore(&pgd_lock, flags);
+ goto out_oom;
+ }
+ }
+
+ /* Copy kernel pmd contents and write-protect the new pmds. */
+ for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++) {
+ unsigned long v = (unsigned long)i << PGDIR_SHIFT;
+ pgd_t *kpgd = pgd_offset_k(v);
+ pud_t *kpud = pud_offset(kpgd, v);
+ pmd_t *kpmd = pmd_offset(kpud, v);
+ memcpy(pmd[i], kpmd, PAGE_SIZE);
+ make_lowmem_page_readonly(
+ pmd[i], XENFEAT_writable_page_tables);
+ }
+
+ /* It is safe to poke machine addresses of pmds under the pmd_lock. */
+ for (i = 0; i < PTRS_PER_PGD; i++)
+ set_pgd(&pgd[i], __pgd(1 + __pa(pmd[i])));
+
+ /* Ensure this pgd gets picked up and pinned on save/restore. */
+ pgd_list_add(pgd);
+
+ spin_unlock_irqrestore(&pgd_lock, flags);
+
+ kfree(pmd);
+
+ return pgd;
+
+out_oom:
+ if (HAVE_SHARED_KERNEL_PMD) {
+ for (i--; i >= 0; i--)
+ kmem_cache_free(pmd_cache,
+ (void *)__va(pgd_val(pgd[i])-1));
+ } else {
+ for (i--; i >= 0; i--)
+ kmem_cache_free(pmd_cache, pmd[i]);
+ kfree(pmd);
+ }
+ kmem_cache_free(pgd_cache, pgd);
+ return NULL;
+}
+
+void pgd_free(pgd_t *pgd)
+{
+ int i;
+
+ /*
+ * After this the pgd should not be pinned for the duration of this
+ * function's execution. We should never sleep and thus never race:
+ * 1. User pmds will not become write-protected under our feet due
+ * to a concurrent mm_pin_all().
+ * 2. The machine addresses in PGD entries will not become invalid
+ * due to a concurrent save/restore.
+ */
+ pgd_test_and_unpin(pgd);
+
+ /* in the PAE case user pgd entries are overwritten before usage */
+ if (PTRS_PER_PMD > 1) {
+ for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
+ pmd_t *pmd = (void *)__va(pgd_val(pgd[i])-1);
+ kmem_cache_free(pmd_cache, pmd);
+ }
+
+ if (!HAVE_SHARED_KERNEL_PMD) {
+ unsigned long flags;
+ spin_lock_irqsave(&pgd_lock, flags);
+ pgd_list_del(pgd);
+ spin_unlock_irqrestore(&pgd_lock, flags);
+
+ for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++) {
+ pmd_t *pmd = (void *)__va(pgd_val(pgd[i])-1);
+ make_lowmem_page_writable(
+ pmd, XENFEAT_writable_page_tables);
+ memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
+ kmem_cache_free(pmd_cache, pmd);
+ }
+
+ if (!xen_feature(XENFEAT_pae_pgdir_above_4gb))
+ xen_destroy_contiguous_region(
+ (unsigned long)pgd, 0);
+ }
+ }
+
+ /* in the non-PAE case, free_pgtables() clears user pgd entries */
+ kmem_cache_free(pgd_cache, pgd);
+}
+
+void make_lowmem_page_readonly(void *va, unsigned int feature)
+{
+ pte_t *pte;
+ int rc;
+
+ if (xen_feature(feature))
+ return;
+
+ pte = virt_to_ptep(va);
+ rc = HYPERVISOR_update_va_mapping(
+ (unsigned long)va, pte_wrprotect(*pte), 0);
+ BUG_ON(rc);
+}
+
+void make_lowmem_page_writable(void *va, unsigned int feature)
+{
+ pte_t *pte;
+ int rc;
+
+ if (xen_feature(feature))
+ return;
+
+ pte = virt_to_ptep(va);
+ rc = HYPERVISOR_update_va_mapping(
+ (unsigned long)va, pte_mkwrite(*pte), 0);
+ BUG_ON(rc);
+}
+
+void make_page_readonly(void *va, unsigned int feature)
+{
+ pte_t *pte;
+ int rc;
+
+ if (xen_feature(feature))
+ return;
+
+ pte = virt_to_ptep(va);
+ rc = HYPERVISOR_update_va_mapping(
+ (unsigned long)va, pte_wrprotect(*pte), 0);
+ if (rc) /* fallback? */
+ xen_l1_entry_update(pte, pte_wrprotect(*pte));
+ if ((unsigned long)va >= (unsigned long)high_memory) {
+ unsigned long pfn = pte_pfn(*pte);
+#ifdef CONFIG_HIGHMEM
+ if (pfn >= highstart_pfn)
+ kmap_flush_unused(); /* flush stale writable kmaps */
+ else
+#endif
+ make_lowmem_page_readonly(
+ phys_to_virt(pfn << PAGE_SHIFT), feature);
+ }
+}
+
+void make_page_writable(void *va, unsigned int feature)
+{
+ pte_t *pte;
+ int rc;
+
+ if (xen_feature(feature))
+ return;
+
+ pte = virt_to_ptep(va);
+ rc = HYPERVISOR_update_va_mapping(
+ (unsigned long)va, pte_mkwrite(*pte), 0);
+ if (rc) /* fallback? */
+ xen_l1_entry_update(pte, pte_mkwrite(*pte));
+ if ((unsigned long)va >= (unsigned long)high_memory) {
+ unsigned long pfn = pte_pfn(*pte);
+#ifdef CONFIG_HIGHMEM
+ if (pfn < highstart_pfn)
+#endif
+ make_lowmem_page_writable(
+ phys_to_virt(pfn << PAGE_SHIFT), feature);
+ }
+}
+
+void make_pages_readonly(void *va, unsigned int nr, unsigned int feature)
+{
+ if (xen_feature(feature))
+ return;
+
+ while (nr-- != 0) {
+ make_page_readonly(va, feature);
+ va = (void *)((unsigned long)va + PAGE_SIZE);
+ }
+}
+
+void make_pages_writable(void *va, unsigned int nr, unsigned int feature)
+{
+ if (xen_feature(feature))
+ return;
+
+ while (nr-- != 0) {
+ make_page_writable(va, feature);
+ va = (void *)((unsigned long)va + PAGE_SIZE);
+ }
+}
+
+static inline void pgd_walk_set_prot(void *pt, pgprot_t flags)
+{
+ struct page *page = virt_to_page(pt);
+ unsigned long pfn = page_to_pfn(page);
+
+ if (PageHighMem(page))
+ return;
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ pfn_pte(pfn, flags), 0));
+}
+
+static void pgd_walk(pgd_t *pgd_base, pgprot_t flags)
+{
+ pgd_t *pgd = pgd_base;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ int g, u, m;
+
+ if (xen_feature(XENFEAT_auto_translated_physmap))
+ return;
+
+ for (g = 0; g < USER_PTRS_PER_PGD; g++, pgd++) {
+ if (pgd_none(*pgd))
+ continue;
+ pud = pud_offset(pgd, 0);
+ if (PTRS_PER_PUD > 1) /* not folded */
+ pgd_walk_set_prot(pud,flags);
+ for (u = 0; u < PTRS_PER_PUD; u++, pud++) {
+ if (pud_none(*pud))
+ continue;
+ pmd = pmd_offset(pud, 0);
+ if (PTRS_PER_PMD > 1) /* not folded */
+ pgd_walk_set_prot(pmd,flags);
+ for (m = 0; m < PTRS_PER_PMD; m++, pmd++) {
+ if (pmd_none(*pmd))
+ continue;
+ pte = pte_offset_kernel(pmd,0);
+ pgd_walk_set_prot(pte,flags);
+ }
+ }
+ }
+
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)pgd_base,
+ pfn_pte(virt_to_phys(pgd_base)>>PAGE_SHIFT, flags),
+ UVMF_TLB_FLUSH));
+}
+
+static void __pgd_pin(pgd_t *pgd)
+{
+ pgd_walk(pgd, PAGE_KERNEL_RO);
+ xen_pgd_pin(__pa(pgd));
+ set_bit(PG_pinned, &virt_to_page(pgd)->flags);
+}
+
+static void __pgd_unpin(pgd_t *pgd)
+{
+ xen_pgd_unpin(__pa(pgd));
+ pgd_walk(pgd, PAGE_KERNEL);
+ clear_bit(PG_pinned, &virt_to_page(pgd)->flags);
+}
+
+static void pgd_test_and_unpin(pgd_t *pgd)
+{
+ if (test_bit(PG_pinned, &virt_to_page(pgd)->flags))
+ __pgd_unpin(pgd);
+}
+
+void mm_pin(struct mm_struct *mm)
+{
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+ spin_lock(&mm->page_table_lock);
+ __pgd_pin(mm->pgd);
+ spin_unlock(&mm->page_table_lock);
+}
+
+void mm_unpin(struct mm_struct *mm)
+{
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+ spin_lock(&mm->page_table_lock);
+ __pgd_unpin(mm->pgd);
+ spin_unlock(&mm->page_table_lock);
+}
+
+void mm_pin_all(void)
+{
+ struct page *page;
+
+ /* Only pgds on the pgd_list please: none hidden in the slab cache. */
+ kmem_cache_shrink(pgd_cache);
+
+ if (xen_feature(XENFEAT_writable_page_tables))
+ return;
+
+ for (page = pgd_list; page; page = (struct page *)page->index) {
+ if (!test_bit(PG_pinned, &page->flags))
+ __pgd_pin((pgd_t *)page_address(page));
+ }
+}
+
+void _arch_dup_mmap(struct mm_struct *mm)
+{
+ if (!test_bit(PG_pinned, &virt_to_page(mm->pgd)->flags))
+ mm_pin(mm);
+}
+
+void _arch_exit_mmap(struct mm_struct *mm)
+{
+ struct task_struct *tsk = current;
+
+ task_lock(tsk);
+
+ /*
+ * We aggressively remove defunct pgd from cr3. We execute unmap_vmas()
+ * *much* faster this way, as no tlb flushes means bigger wrpt batches.
+ */
+ if (tsk->active_mm == mm) {
+ tsk->active_mm = &init_mm;
+ atomic_inc(&init_mm.mm_count);
+
+ switch_mm(mm, &init_mm, tsk);
+
+ atomic_dec(&mm->mm_count);
+ BUG_ON(atomic_read(&mm->mm_count) == 0);
+ }
+
+ task_unlock(tsk);
+
+ if (test_bit(PG_pinned, &virt_to_page(mm->pgd)->flags) &&
+ (atomic_read(&mm->mm_count) == 1) &&
+ !mm->context.has_foreign_mappings)
+ mm_unpin(mm);
+}
git://git.onelab.eu / linux-2.6.git / blobdiff