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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:41 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:42 -0700
commitf412ac08c9861b4791af0145934c22f1458686da (patch)
tree5e515efa116f3968c2caa75bc691a197199313a8 /include
parent4c21e2f2441dc5fbb957b030333f5a3f2d02dea7 (diff)
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[PATCH] mm: fix rss and mmlist locking
A couple of oddities were guarded by page_table_lock, no longer properly guarded when that is split. The mm_counters of file_rss and anon_rss: make those an atomic_t, or an atomic64_t if the architecture supports it, in such a case. Definitions by courtesy of Christoph Lameter: who spent considerable effort on more scalable ways of counting, but found insufficient benefit in practice. And adding an mm with swap to the mmlist for swapoff: the list is well- guarded by its own lock, but the list_empty check now has to be repeated inside it. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h42
1 files changed, 38 insertions, 4 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 292cb57ce38f..1c30bc308ef1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -249,13 +249,47 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
extern void arch_unmap_area(struct mm_struct *, unsigned long);
extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
+#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+/*
+ * The mm counters are not protected by its page_table_lock,
+ * so must be incremented atomically.
+ */
+#ifdef ATOMIC64_INIT
+#define set_mm_counter(mm, member, value) atomic64_set(&(mm)->_##member, value)
+#define get_mm_counter(mm, member) ((unsigned long)atomic64_read(&(mm)->_##member))
+#define add_mm_counter(mm, member, value) atomic64_add(value, &(mm)->_##member)
+#define inc_mm_counter(mm, member) atomic64_inc(&(mm)->_##member)
+#define dec_mm_counter(mm, member) atomic64_dec(&(mm)->_##member)
+typedef atomic64_t mm_counter_t;
+#else /* !ATOMIC64_INIT */
+/*
+ * The counters wrap back to 0 at 2^32 * PAGE_SIZE,
+ * that is, at 16TB if using 4kB page size.
+ */
+#define set_mm_counter(mm, member, value) atomic_set(&(mm)->_##member, value)
+#define get_mm_counter(mm, member) ((unsigned long)atomic_read(&(mm)->_##member))
+#define add_mm_counter(mm, member, value) atomic_add(value, &(mm)->_##member)
+#define inc_mm_counter(mm, member) atomic_inc(&(mm)->_##member)
+#define dec_mm_counter(mm, member) atomic_dec(&(mm)->_##member)
+typedef atomic_t mm_counter_t;
+#endif /* !ATOMIC64_INIT */
+
+#else /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+/*
+ * The mm counters are protected by its page_table_lock,
+ * so can be incremented directly.
+ */
#define set_mm_counter(mm, member, value) (mm)->_##member = (value)
#define get_mm_counter(mm, member) ((mm)->_##member)
#define add_mm_counter(mm, member, value) (mm)->_##member += (value)
#define inc_mm_counter(mm, member) (mm)->_##member++
#define dec_mm_counter(mm, member) (mm)->_##member--
-#define get_mm_rss(mm) ((mm)->_file_rss + (mm)->_anon_rss)
+typedef unsigned long mm_counter_t;
+
+#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#define get_mm_rss(mm) \
+ (get_mm_counter(mm, file_rss) + get_mm_counter(mm, anon_rss))
#define update_hiwater_rss(mm) do { \
unsigned long _rss = get_mm_rss(mm); \
if ((mm)->hiwater_rss < _rss) \
@@ -266,8 +300,6 @@ extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);
(mm)->hiwater_vm = (mm)->total_vm; \
} while (0)
-typedef unsigned long mm_counter_t;
-
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs */
struct rb_root mm_rb;
@@ -291,7 +323,9 @@ struct mm_struct {
* by mmlist_lock
*/
- /* Special counters protected by the page_table_lock */
+ /* Special counters, in some configurations protected by the
+ * page_table_lock, in other configurations by being atomic.
+ */
mm_counter_t _file_rss;
mm_counter_t _anon_rss;