diff options
| -rw-r--r-- | Documentation/sysctl/vm.txt | 12 | ||||
| -rw-r--r-- | Documentation/vm/overcommit-accounting | 7 | ||||
| -rw-r--r-- | include/linux/mm.h | 9 | ||||
| -rw-r--r-- | include/linux/mman.h | 1 | ||||
| -rw-r--r-- | kernel/sysctl.c | 11 | ||||
| -rw-r--r-- | mm/mmap.c | 1 | ||||
| -rw-r--r-- | mm/nommu.c | 1 | ||||
| -rw-r--r-- | mm/util.c | 36 |
8 files changed, 70 insertions, 8 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 1fbd4eb7b64a..9f5481bdc5a4 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -47,6 +47,7 @@ Currently, these files are in /proc/sys/vm: - numa_zonelist_order - oom_dump_tasks - oom_kill_allocating_task +- overcommit_kbytes - overcommit_memory - overcommit_ratio - page-cluster @@ -574,6 +575,17 @@ The default value is 0. ============================================================== +overcommit_kbytes: + +When overcommit_memory is set to 2, the committed address space is not +permitted to exceed swap plus this amount of physical RAM. See below. + +Note: overcommit_kbytes is the counterpart of overcommit_ratio. Only one +of them may be specified at a time. Setting one disables the other (which +then appears as 0 when read). + +============================================================== + overcommit_memory: This value contains a flag that enables memory overcommitment. diff --git a/Documentation/vm/overcommit-accounting b/Documentation/vm/overcommit-accounting index 8eaa2fc4b8fa..cbfaaa674118 100644 --- a/Documentation/vm/overcommit-accounting +++ b/Documentation/vm/overcommit-accounting @@ -14,8 +14,8 @@ The Linux kernel supports the following overcommit handling modes 2 - Don't overcommit. The total address space commit for the system is not permitted to exceed swap + a - configurable percentage (default is 50) of physical RAM. - Depending on the percentage you use, in most situations + configurable amount (default is 50%) of physical RAM. + Depending on the amount you use, in most situations this means a process will not be killed while accessing pages but will receive errors on memory allocation as appropriate. @@ -26,7 +26,8 @@ The Linux kernel supports the following overcommit handling modes The overcommit policy is set via the sysctl `vm.overcommit_memory'. -The overcommit percentage is set via `vm.overcommit_ratio'. +The overcommit amount can be set via `vm.overcommit_ratio' (percentage) +or `vm.overcommit_kbytes' (absolute value). The current overcommit limit and amount committed are viewable in /proc/meminfo as CommitLimit and Committed_AS respectively. diff --git a/include/linux/mm.h b/include/linux/mm.h index 4c0c01afc19b..a512dd836931 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -57,6 +57,15 @@ extern int sysctl_legacy_va_layout; extern unsigned long sysctl_user_reserve_kbytes; extern unsigned long sysctl_admin_reserve_kbytes; +extern int sysctl_overcommit_memory; +extern int sysctl_overcommit_ratio; +extern unsigned long sysctl_overcommit_kbytes; + +extern int overcommit_ratio_handler(struct ctl_table *, int, void __user *, + size_t *, loff_t *); +extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *, + size_t *, loff_t *); + #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) /* to align the pointer to the (next) page boundary */ diff --git a/include/linux/mman.h b/include/linux/mman.h index 7f7f8dae4b1d..16373c8f5f57 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -9,6 +9,7 @@ extern int sysctl_overcommit_memory; extern int sysctl_overcommit_ratio; +extern unsigned long sysctl_overcommit_kbytes; extern struct percpu_counter vm_committed_as; #ifdef CONFIG_SMP diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c8da99f905cf..332cefcdb04b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -95,8 +95,6 @@ #if defined(CONFIG_SYSCTL) /* External variables not in a header file. */ -extern int sysctl_overcommit_memory; -extern int sysctl_overcommit_ratio; extern int max_threads; extern int suid_dumpable; #ifdef CONFIG_COREDUMP @@ -1121,7 +1119,14 @@ static struct ctl_table vm_table[] = { .data = &sysctl_overcommit_ratio, .maxlen = sizeof(sysctl_overcommit_ratio), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = overcommit_ratio_handler, + }, + { + .procname = "overcommit_kbytes", + .data = &sysctl_overcommit_kbytes, + .maxlen = sizeof(sysctl_overcommit_kbytes), + .mode = 0644, + .proc_handler = overcommit_kbytes_handler, }, { .procname = "page-cluster", diff --git a/mm/mmap.c b/mm/mmap.c index 834b2d785f1e..39552de6e1db 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -86,6 +86,7 @@ EXPORT_SYMBOL(vm_get_page_prot); int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ +unsigned long sysctl_overcommit_kbytes __read_mostly; int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ diff --git a/mm/nommu.c b/mm/nommu.c index fec093adad9c..8740213b1647 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -60,6 +60,7 @@ unsigned long highest_memmap_pfn; struct percpu_counter vm_committed_as; int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ int sysctl_overcommit_ratio = 50; /* default is 50% */ +unsigned long sysctl_overcommit_kbytes __read_mostly; int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ diff --git a/mm/util.c b/mm/util.c index 808f375648e7..a24aa22f2473 100644 --- a/mm/util.c +++ b/mm/util.c @@ -404,13 +404,45 @@ struct address_space *page_mapping(struct page *page) return mapping; } +int overcommit_ratio_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret; + + ret = proc_dointvec(table, write, buffer, lenp, ppos); + if (ret == 0 && write) + sysctl_overcommit_kbytes = 0; + return ret; +} + +int overcommit_kbytes_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret; + + ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); + if (ret == 0 && write) + sysctl_overcommit_ratio = 0; + return ret; +} + /* * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used */ unsigned long vm_commit_limit(void) { - return ((totalram_pages - hugetlb_total_pages()) - * sysctl_overcommit_ratio / 100) + total_swap_pages; + unsigned long allowed; + + if (sysctl_overcommit_kbytes) + allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10); + else + allowed = ((totalram_pages - hugetlb_total_pages()) + * sysctl_overcommit_ratio / 100); + allowed += total_swap_pages; + + return allowed; } |