Add ulimit API for users. When memory is not enough,
user's app will receive a signal, and it can do something
in the handler.
e.g.
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
void handler(int sig)
{
char *b = malloc(1000000000);
memset(b, '\0', 1000000000);
printf("catch the signal by wwy\n");
exit(1);
}
int main ( int argc, char *argv[] )
{
struct rlimit r1 = { 3600000000, 3600000000};
setrlimit(RLIMIT_AS, &r1);
signal(47, &handler);
char * a = malloc(3600000000);
int fd=open("/home/wayne/qemu.tar.bz2", O_RDONLY);
char abc[2000000] = {'\0'};
mmap(NULL, 10000000, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd , 0);
sleep(100);
free(a);
while(1){
}
}
RTOS-x86_64 /tmp # ./a.out
catch the signal by wwy
Signed-off-by: Xishi Qiu <qiuxi...@huawei.com>
diff --git a/mm/Makefile b/mm/Makefile
index 9c60f76..a5dec90 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -18,6 +18,7 @@ obj-y += init-mm.o
ifdef CONFIG_OOM_EXTEND
obj-y += oom_extend.o pagecache_info.o
endif
+obj-y += ulimit-init.o
obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
diff --git a/mm/mmap.c b/mm/mmap.c
index 4ff7f52..a10155f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2402,6 +2402,11 @@ struct vm_area_struct *copy_vma(struct vm_area_struct
**vmap,
* Return true if the calling process may expand its vm space by the passed
* number of pages
*/
+
+#ifdef CONFIG_ULIMIT_VM_SIG
+unsigned long vm_expand_signal_enable = 0;
+EXPORT_SYMBOL(vm_expand_signal_enable);
+#endif
+
int may_expand_vm(struct mm_struct *mm, unsigned long npages)
{
unsigned long cur = mm->total_vm; /* pages */
@@ -2410,7 +2415,9 @@ int may_expand_vm(struct mm_struct *mm, unsigned long
npages)
lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
if (cur + npages > lim){
- send_sig(SIGRTMIN+15, current, 1);
+#ifdef CONFIG_ULIMIT_VM_SIG
+ if (vm_expand_signal_enable){
+ send_sig(SIGRTMIN+15, current, 1);
+ }
+#endif
return 0;
}
return 1;
diff --git a/mm/ulimit-init.c b/mm/ulimit-init.c
new file mode 100644
index 0000000..d3b3a76
--- /dev/null
+++ b/mm/ulimit-init.c
@@ -0,0 +1,65 @@
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+
+static struct kobject *ulimit_kobj;
+extern unsigned long vm_expand_signal_enable;
+
+static ssize_t show(struct kobject *kobj, struct kobj_attribut *attr, char*
buf)
+{
+ return snprintf(buf, 10, "%lu\n", vm_expand_signal_enable);
+}
+
+static ssize_t store(struct kobject *kobj, struct kobj_attribute *attr, const
char *buf, size_t count)
+{
+ unsigned long enable;
+ if (0 != strict_strtoul(buf, 10, &enable))
+ return -EINVAL;
+ if (0 != enable && 1 != enable){
+ return -EINVAL;
+ }
+
+ vm_expand_signal_enable = enable;
+ return count;
+}
+
+static struct kobj_attribute ulimit_vm_attribute =
+__ATTR(vm_expand_signal_enable, 0644, show, store);
+
+static struct attribute *attrs[] = {
+ &ulimit_vm_attribute.attr,
+ NULL, /* need to NULL terminate the list of attributes */
+};
+
+static struct attribute_group attr_group = {
+ .attrs = attrs,
+};
+
+
+static int ulimit_obj_init(void)
+{
+ int retval;
+
+ ulimit_kobj = kobject_create_and_add("ulimit", mm_kobj);
+
+ if (!ulimit_kobj)
+ return -ENOMEM;
+
+ retval = sysfs_create_group(ulimit_kobj, &attr_group);
+
+ return retval;
+}
+
+static int ulimit_obj_exit(void)
+{
+ sysfs_remove_group(ulimit_kobj, &attr_group);
+ kobject_put(ulimit_kobj);
+ return 0;
+}
+
+module_init(ulimit_obj_init);
+module_exit(ulimit_obj_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Wayne");
diff --git a/mm/Kconfig b/mm/Kconfig
index ef891af..dc9c881 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -295,3 +295,6 @@ config NOMMU_INITIAL_TRIM_EXCESS
of 1 says that all excess pages should be trimmed.
See Documentation/nommu-mmap.txt for more information.
+config ULIMIT_VM_SIG
+ bool "vm expand send SIG 47"
diff --git a/mm/Makefile b/mm/Makefile
index a5dec90..5c4d70f 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -18,8 +18,9 @@ obj-y += init-mm.o
ifdef CONFIG_OOM_EXTEND
obj-y += oom_extend.o pagecache_info.o
endif
+ifdef CONFIG_ULIMIT_VM_SIG
obj-y += ulimit-init.o
-
+endif
obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
obj-$(CONFIG_HAS_DMA) += dmapool.o
--
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