Perform a mechanical rename of mm_struct->map_count to vma_count.
The name "map_count" is ambiguous. It can be confused with other counters like the page mapcount (page->_mapcount), which tracks PTE references.
The new name, vma_count, is more precise and self-documenting, as this field has always counted the number of vm_area_structs associated with an mm_struct. This change improves code clarity and readability.
While at it, update the BUG_ON() in exit_mmap() to a WARN_ON_ONCE() to avoid crashing the kernel on a simple accounting mismatch. No other functional change is intended.
Signed-off-by: Kalesh Singh kaleshsingh@google.com ---
Changes in v4: - Update the new max_vma_count_tests.c to use the vma_count name.
Changes in v3: - Change vma_count BUG_ON() in exit_mmap() to WARN_ON_ONCE, per David and Lorenzo - Collect Reviewed-by tags
fs/binfmt_elf.c | 2 +- fs/coredump.c | 2 +- include/linux/mm_types.h | 2 +- kernel/fork.c | 2 +- mm/debug.c | 2 +- mm/mmap.c | 6 ++-- mm/mremap.c | 4 +-- mm/nommu.c | 8 ++--- mm/vma.c | 30 ++++++++--------- .../selftests/mm/max_vma_count_tests.c | 28 ++++++++-------- tools/testing/vma/vma.c | 32 +++++++++---------- tools/testing/vma/vma_internal.h | 2 +- 12 files changed, 60 insertions(+), 60 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index e4653bb99946..a5acfe97612d 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1660,7 +1660,7 @@ static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm data[0] = count; data[1] = PAGE_SIZE; /* - * Count usually is less than mm->map_count, + * Count usually is less than mm->vma_count, * we need to move filenames down. */ n = cprm->vma_count - count; diff --git a/fs/coredump.c b/fs/coredump.c index b5fc06a092a4..5e0859813141 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1733,7 +1733,7 @@ static bool dump_vma_snapshot(struct coredump_params *cprm)
cprm->vma_data_size = 0; gate_vma = get_gate_vma(mm); - cprm->vma_count = mm->map_count + (gate_vma ? 1 : 0); + cprm->vma_count = mm->vma_count + (gate_vma ? 1 : 0);
cprm->vma_meta = kvmalloc_array(cprm->vma_count, sizeof(*cprm->vma_meta), GFP_KERNEL); if (!cprm->vma_meta) { diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 5021047485a9..2a102f4899ed 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1085,7 +1085,7 @@ struct mm_struct { #ifdef CONFIG_MMU atomic_long_t pgtables_bytes; /* size of all page tables */ #endif - int map_count; /* number of VMAs */ + int vma_count; /* number of VMAs */
spinlock_t page_table_lock; /* Protects page tables and some * counters diff --git a/kernel/fork.c b/kernel/fork.c index dd0bb5fe4305..b2c2ca8a0a9d 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1038,7 +1038,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, mmap_init_lock(mm); INIT_LIST_HEAD(&mm->mmlist); mm_pgtables_bytes_init(mm); - mm->map_count = 0; + mm->vma_count = 0; mm->locked_vm = 0; atomic64_set(&mm->pinned_vm, 0); memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); diff --git a/mm/debug.c b/mm/debug.c index 64ddb0c4b4be..a35e2912ae53 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -204,7 +204,7 @@ void dump_mm(const struct mm_struct *mm) mm->pgd, atomic_read(&mm->mm_users), atomic_read(&mm->mm_count), mm_pgtables_bytes(mm), - mm->map_count, + mm->vma_count, mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm, (u64)atomic64_read(&mm->pinned_vm), mm->data_vm, mm->exec_vm, mm->stack_vm, diff --git a/mm/mmap.c b/mm/mmap.c index 5a967a307099..647a676c0ab4 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -383,7 +383,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, * sysctl_max_map_count limit by one. This behavior is preserved to * avoid breaking existing applications. */ - if (max_vma_count() - mm->map_count < 0) + if (max_vma_count() - mm->vma_count < 0) return -ENOMEM;
/* @@ -1314,7 +1314,7 @@ void exit_mmap(struct mm_struct *mm) vma = vma_next(&vmi); } while (vma && likely(!xa_is_zero(vma)));
- BUG_ON(count != mm->map_count); + WARN_ON_ONCE(count != mm->vma_count);
trace_exit_mmap(mm); destroy: @@ -1822,7 +1822,7 @@ __latent_entropy int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) */ vma_iter_bulk_store(&vmi, tmp);
- mm->map_count++; + mm->vma_count++;
if (tmp->vm_ops && tmp->vm_ops->open) tmp->vm_ops->open(tmp); diff --git a/mm/mremap.c b/mm/mremap.c index 02c38fd957e4..4874729cd65c 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1040,7 +1040,7 @@ static unsigned long prep_move_vma(struct vma_remap_struct *vrm) * We'd prefer to avoid failure later on in do_munmap: * which may split one vma into three before unmapping. */ - if (max_vma_count() - current->mm->map_count < 4) + if (max_vma_count() - current->mm->vma_count < 4) return -ENOMEM;
if (vma->vm_ops && vma->vm_ops->may_split) { @@ -1814,7 +1814,7 @@ static unsigned long check_mremap_params(struct vma_remap_struct *vrm) * the threshold. In other words, is the current map count + 6 at or * below the threshold? Otherwise return -ENOMEM here to be more safe. */ - if (max_vma_count() - current->mm->map_count < 6) + if (max_vma_count() - current->mm->vma_count < 6) return -ENOMEM;
return 0; diff --git a/mm/nommu.c b/mm/nommu.c index ae2b20cc324a..ef05d5abbe9f 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -577,7 +577,7 @@ static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
static void cleanup_vma_from_mm(struct vm_area_struct *vma) { - vma->vm_mm->map_count--; + vma->vm_mm->vma_count--; /* remove the VMA from the mapping */ if (vma->vm_file) { struct address_space *mapping; @@ -1199,7 +1199,7 @@ unsigned long do_mmap(struct file *file, goto error_just_free;
setup_vma_to_mm(vma, current->mm); - current->mm->map_count++; + current->mm->vma_count++; /* add the VMA to the tree */ vma_iter_store_new(&vmi, vma);
@@ -1317,7 +1317,7 @@ static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, return -ENOMEM;
mm = vma->vm_mm; - if (max_vma_count() - mm->map_count < 1) + if (max_vma_count() - mm->vma_count < 1) return -ENOMEM;
region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); @@ -1367,7 +1367,7 @@ static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, setup_vma_to_mm(vma, mm); setup_vma_to_mm(new, mm); vma_iter_store_new(vmi, new); - mm->map_count++; + mm->vma_count++; return 0;
err_vmi_preallocate: diff --git a/mm/vma.c b/mm/vma.c index 768d216beed3..fbb8d1a0449d 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -354,7 +354,7 @@ static void vma_complete(struct vma_prepare *vp, struct vma_iterator *vmi, * (it may either follow vma or precede it). */ vma_iter_store_new(vmi, vp->insert); - mm->map_count++; + mm->vma_count++; }
if (vp->anon_vma) { @@ -385,7 +385,7 @@ static void vma_complete(struct vma_prepare *vp, struct vma_iterator *vmi, } if (vp->remove->anon_vma) anon_vma_merge(vp->vma, vp->remove); - mm->map_count--; + mm->vma_count--; mpol_put(vma_policy(vp->remove)); if (!vp->remove2) WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end); @@ -594,7 +594,7 @@ __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, unsigned long addr, int new_below) { - if (max_vma_count() - vma->vm_mm->map_count < 1) + if (max_vma_count() - vma->vm_mm->vma_count < 1) return -ENOMEM;
return __split_vma(vmi, vma, addr, new_below); @@ -685,13 +685,13 @@ void validate_mm(struct mm_struct *mm) } #endif /* Check for a infinite loop */ - if (++i > mm->map_count + 10) { + if (++i > mm->vma_count + 10) { i = -1; break; } } - if (i != mm->map_count) { - pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i); + if (i != mm->vma_count) { + pr_emerg("vma_count %d vma iterator %d\n", mm->vma_count, i); bug = 1; } VM_BUG_ON_MM(bug, mm); @@ -1268,7 +1268,7 @@ static void vms_complete_munmap_vmas(struct vma_munmap_struct *vms, struct mm_struct *mm;
mm = current->mm; - mm->map_count -= vms->vma_count; + mm->vma_count -= vms->vma_count; mm->locked_vm -= vms->locked_vm; if (vms->unlock) mmap_write_downgrade(mm); @@ -1342,14 +1342,14 @@ static int vms_gather_munmap_vmas(struct vma_munmap_struct *vms, if (vms->start > vms->vma->vm_start) {
/* - * Make sure that map_count on return from munmap() will + * Make sure that vma_count on return from munmap() will * not exceed its limit; but let map_count go just above * its limit temporarily, to help free resources as expected. */ if (vms->end < vms->vma->vm_end && - max_vma_count() - vms->vma->vm_mm->map_count < 1) { + max_vma_count() - vms->vma->vm_mm->vma_count < 1) { error = -ENOMEM; - goto map_count_exceeded; + goto vma_count_exceeded; }
/* Don't bother splitting the VMA if we can't unmap it anyway */ @@ -1463,7 +1463,7 @@ static int vms_gather_munmap_vmas(struct vma_munmap_struct *vms, modify_vma_failed: reattach_vmas(mas_detach); start_split_failed: -map_count_exceeded: +vma_count_exceeded: return error; }
@@ -1781,7 +1781,7 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) vma_start_write(vma); vma_iter_store_new(&vmi, vma); vma_link_file(vma, /* hold_rmap_lock= */false); - mm->map_count++; + mm->vma_count++; validate_mm(mm); return 0; } @@ -2498,7 +2498,7 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap) /* Lock the VMA since it is modified after insertion into VMA tree */ vma_start_write(vma); vma_iter_store_new(vmi, vma); - map->mm->map_count++; + map->mm->vma_count++; vma_link_file(vma, map->hold_file_rmap_lock);
/* @@ -2819,7 +2819,7 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, * typically extends the existing brk VMA rather than creating a new one. * See also the comment in do_mmap(). */ - if (max_vma_count() - mm->map_count < 0) + if (max_vma_count() - mm->vma_count < 0) return -ENOMEM;
if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) @@ -2857,7 +2857,7 @@ int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) goto mas_store_fail;
- mm->map_count++; + mm->vma_count++; validate_mm(mm); out: perf_event_mmap(vma); diff --git a/tools/testing/selftests/mm/max_vma_count_tests.c b/tools/testing/selftests/mm/max_vma_count_tests.c index e20cafaefc82..79404cb22df2 100644 --- a/tools/testing/selftests/mm/max_vma_count_tests.c +++ b/tools/testing/selftests/mm/max_vma_count_tests.c @@ -18,7 +18,7 @@ #include "../kselftest_harness.h" #include "vm_util.h"
-#define DEFAULT_MAX_MAP_COUNT 65530 +#define DEFAULT_MAX_VMA_COUNT 65530 #define TEST_AREA_NR_PAGES 3 #define TEST_AREA_PROT (PROT_NONE) #define EXTRA_MAP_PROT (PROT_NONE) @@ -42,9 +42,9 @@ static int get_max_vma_count(void); static bool set_max_vma_count(int val); static int get_current_vma_count(void); static bool is_test_area_mapped(char *test_area, int test_area_size); -static bool lower_max_map_count_if_needed(max_vma_count_data_t *self, +static bool lower_max_vma_count_if_needed(max_vma_count_data_t *self, struct __test_metadata *_metadata); -static void restore_max_map_count_if_needed(max_vma_count_data_t *self, +static void restore_max_vma_count_if_needed(max_vma_count_data_t *self, struct __test_metadata *_metadata); static bool free_vma_slots(max_vma_count_data_t *self, int slots_to_free); static void create_reservation(max_vma_count_data_t *self, @@ -98,9 +98,9 @@ FIXTURE_SETUP(max_vma_count)
self->test_area_size = TEST_AREA_NR_PAGES * psize();
- if (!lower_max_map_count_if_needed(self, _metadata)) { + if (!lower_max_vma_count_if_needed(self, _metadata)) { SKIP(return, - "max_map_count too high and cannot be lowered. Please rerun as root."); + "max_vma_count too high and cannot be lowered. Please rerun as root."); }
initial_vma_count = get_current_vma_count(); @@ -127,7 +127,7 @@ FIXTURE_TEARDOWN(max_vma_count) * mapping cleanup to process teardown for simplicity. */
- restore_max_map_count_if_needed(self, _metadata); + restore_max_vma_count_if_needed(self, _metadata); }
static bool mmap_anon(max_vma_count_data_t *self) @@ -542,7 +542,7 @@ TEST_HARNESS_MAIN
/* --- Utilities --- */
-static bool lower_max_map_count_if_needed(max_vma_count_data_t *self, +static bool lower_max_vma_count_if_needed(max_vma_count_data_t *self, struct __test_metadata *_metadata) { self->max_vma_count = get_max_vma_count(); @@ -550,19 +550,19 @@ static bool lower_max_map_count_if_needed(max_vma_count_data_t *self, ASSERT_GT(self->max_vma_count, 0);
self->original_max_vma_count = 0; - if (self->max_vma_count > DEFAULT_MAX_MAP_COUNT) { + if (self->max_vma_count > DEFAULT_MAX_VMA_COUNT) { self->original_max_vma_count = self->max_vma_count; TH_LOG("Max VMA count: %d; lowering to default %d for test...", - self->max_vma_count, DEFAULT_MAX_MAP_COUNT); + self->max_vma_count, DEFAULT_MAX_VMA_COUNT);
- if (!set_max_vma_count(DEFAULT_MAX_MAP_COUNT)) + if (!set_max_vma_count(DEFAULT_MAX_VMA_COUNT)) return false; - self->max_vma_count = DEFAULT_MAX_MAP_COUNT; + self->max_vma_count = DEFAULT_MAX_VMA_COUNT; } return true; }
-static void restore_max_map_count_if_needed(max_vma_count_data_t *self, +static void restore_max_vma_count_if_needed(max_vma_count_data_t *self, struct __test_metadata *_metadata) { if (!self->original_max_vma_count) @@ -572,7 +572,7 @@ static void restore_max_map_count_if_needed(max_vma_count_data_t *self, return;
if (!set_max_vma_count(self->original_max_vma_count)) - TH_LOG("Failed to restore max_map_count to %d", + TH_LOG("Failed to restore max_vma_count to %d", self->original_max_vma_count); }
@@ -617,7 +617,7 @@ static int get_current_vma_count(void)
/* * The [vsyscall] mapping is a special mapping that - * doesn't count against the max_map_count limit. + * doesn't count against the max_vma_count limit. * Ignore it here to match the kernel's accounting. */ if (strcmp(vma_name, "[vsyscall]") != 0) diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c index 656e1c75b711..69fa7d14a6c2 100644 --- a/tools/testing/vma/vma.c +++ b/tools/testing/vma/vma.c @@ -261,7 +261,7 @@ static int cleanup_mm(struct mm_struct *mm, struct vma_iterator *vmi) }
mtree_destroy(&mm->mm_mt); - mm->map_count = 0; + mm->vma_count = 0; return count; }
@@ -500,7 +500,7 @@ static bool test_merge_new(void) INIT_LIST_HEAD(&vma_d->anon_vma_chain); list_add(&dummy_anon_vma_chain_d.same_vma, &vma_d->anon_vma_chain); ASSERT_FALSE(merged); - ASSERT_EQ(mm.map_count, 4); + ASSERT_EQ(mm.vma_count, 4);
/* * Merge BOTH sides. @@ -519,7 +519,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 3); + ASSERT_EQ(mm.vma_count, 3);
/* * Merge to PREVIOUS VMA. @@ -536,7 +536,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 3); + ASSERT_EQ(mm.vma_count, 3);
/* * Merge to NEXT VMA. @@ -555,7 +555,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 6); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 3); + ASSERT_EQ(mm.vma_count, 3);
/* * Merge BOTH sides. @@ -573,7 +573,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
/* * Merge to NEXT VMA. @@ -591,7 +591,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 0xa); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
/* * Merge BOTH sides. @@ -608,7 +608,7 @@ static bool test_merge_new(void) ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_EQ(vma->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 1); + ASSERT_EQ(mm.vma_count, 1);
/* * Final state. @@ -967,7 +967,7 @@ static bool test_vma_merge_new_with_close(void) ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_EQ(vma->vm_ops, &vm_ops); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
cleanup_mm(&mm, &vmi); return true; @@ -1017,7 +1017,7 @@ static bool test_merge_existing(void) ASSERT_EQ(vma->vm_pgoff, 2); ASSERT_TRUE(vma_write_started(vma)); ASSERT_TRUE(vma_write_started(vma_next)); - ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
/* Clear down and reset. */ ASSERT_EQ(cleanup_mm(&mm, &vmi), 2); @@ -1045,7 +1045,7 @@ static bool test_merge_existing(void) ASSERT_EQ(vma_next->vm_pgoff, 2); ASSERT_EQ(vma_next->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_next)); - ASSERT_EQ(mm.map_count, 1); + ASSERT_EQ(mm.vma_count, 1);
/* Clear down and reset. We should have deleted vma. */ ASSERT_EQ(cleanup_mm(&mm, &vmi), 1); @@ -1079,7 +1079,7 @@ static bool test_merge_existing(void) ASSERT_EQ(vma->vm_pgoff, 6); ASSERT_TRUE(vma_write_started(vma_prev)); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
/* Clear down and reset. */ ASSERT_EQ(cleanup_mm(&mm, &vmi), 2); @@ -1108,7 +1108,7 @@ static bool test_merge_existing(void) ASSERT_EQ(vma_prev->vm_pgoff, 0); ASSERT_EQ(vma_prev->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_prev)); - ASSERT_EQ(mm.map_count, 1); + ASSERT_EQ(mm.vma_count, 1);
/* Clear down and reset. We should have deleted vma. */ ASSERT_EQ(cleanup_mm(&mm, &vmi), 1); @@ -1138,7 +1138,7 @@ static bool test_merge_existing(void) ASSERT_EQ(vma_prev->vm_pgoff, 0); ASSERT_EQ(vma_prev->anon_vma, &dummy_anon_vma); ASSERT_TRUE(vma_write_started(vma_prev)); - ASSERT_EQ(mm.map_count, 1); + ASSERT_EQ(mm.vma_count, 1);
/* Clear down and reset. We should have deleted prev and next. */ ASSERT_EQ(cleanup_mm(&mm, &vmi), 1); @@ -1540,7 +1540,7 @@ static bool test_merge_extend(void) ASSERT_EQ(vma->vm_end, 0x4000); ASSERT_EQ(vma->vm_pgoff, 0); ASSERT_TRUE(vma_write_started(vma)); - ASSERT_EQ(mm.map_count, 1); + ASSERT_EQ(mm.vma_count, 1);
cleanup_mm(&mm, &vmi); return true; @@ -1652,7 +1652,7 @@ static bool test_mmap_region_basic(void) 0x24d, NULL); ASSERT_EQ(addr, 0x24d000);
- ASSERT_EQ(mm.map_count, 2); + ASSERT_EQ(mm.vma_count, 2);
for_each_vma(vmi, vma) { if (vma->vm_start == 0x300000) { diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h index 41d354a699c5..d89b26e81679 100644 --- a/tools/testing/vma/vma_internal.h +++ b/tools/testing/vma/vma_internal.h @@ -261,7 +261,7 @@ typedef struct {
struct mm_struct { struct maple_tree mm_mt; - int map_count; /* number of VMAs */ + int vma_count; /* number of VMAs */ unsigned long total_vm; /* Total pages mapped */ unsigned long locked_vm; /* Pages that have PG_mlocked set */ unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */