* Address space accounting code <alan@lxorguk.ukuu.org.uk>
*/
+#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/mm.h>
#include <linux/uprobes.h>
#include <linux/rbtree_augmented.h>
#include <linux/sched/sysctl.h>
+#include <linux/notifier.h>
+#include <linux/memory.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
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 */
/*
* Make sure vm_committed_as in one cacheline and not cacheline shared with
* other variables. It can be updated by several CPUs frequently.
free -= totalreserve_pages;
/*
- * Leave the last 3% for root
+ * Reserve some for root
*/
if (!cap_sys_admin)
- free -= free / 32;
+ free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
if (free > pages)
return 0;
allowed = (totalram_pages - hugetlb_total_pages())
* sysctl_overcommit_ratio / 100;
/*
- * Leave the last 3% for root
+ * Reserve some for root
*/
if (!cap_sys_admin)
- allowed -= allowed / 32;
+ allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
allowed += total_swap_pages;
/*
return 0;
}
+static unsigned long count_vma_pages_range(struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
+{
+ unsigned long nr_pages = 0;
+ struct vm_area_struct *vma;
+
+ /* Find first overlaping mapping */
+ vma = find_vma_intersection(mm, addr, end);
+ if (!vma)
+ return 0;
+
+ nr_pages = (min(end, vma->vm_end) -
+ max(addr, vma->vm_start)) >> PAGE_SHIFT;
+
+ /* Iterate over the rest of the overlaps */
+ for (vma = vma->vm_next; vma; vma = vma->vm_next) {
+ unsigned long overlap_len;
+
+ if (vma->vm_start > end)
+ break;
+
+ overlap_len = min(end, vma->vm_end) - vma->vm_start;
+ nr_pages += overlap_len >> PAGE_SHIFT;
+ }
+
+ return nr_pages;
+}
+
void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
struct rb_node **rb_link, struct rb_node *rb_parent)
{
unsigned long charged = 0;
struct inode *inode = file ? file_inode(file) : NULL;
+ /* Check against address space limit. */
+ if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
+ unsigned long nr_pages;
+
+ /*
+ * MAP_FIXED may remove pages of mappings that intersects with
+ * requested mapping. Account for the pages it would unmap.
+ */
+ if (!(vm_flags & MAP_FIXED))
+ return -ENOMEM;
+
+ nr_pages = count_vma_pages_range(mm, addr, addr + len);
+
+ if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
+ return -ENOMEM;
+ }
+
/* Clear old maps */
error = -ENOMEM;
munmap_back:
goto munmap_back;
}
- /* Check against address space limit. */
- if (!may_expand_vm(mm, len >> PAGE_SHIFT))
- return -ENOMEM;
-
/*
* Private writable mapping: check memory availability
*/
* The default value is min(3% of free memory, 128MB)
* 128MB is enough to recover with sshd/login, bash, and top/kill.
*/
-static int __meminit init_user_reserve(void)
+static int init_user_reserve(void)
{
unsigned long free_kbytes;
return 0;
}
module_init(init_user_reserve)
+
+/*
+ * Initialise sysctl_admin_reserve_kbytes.
+ *
+ * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
+ * to log in and kill a memory hogging process.
+ *
+ * Systems with more than 256MB will reserve 8MB, enough to recover
+ * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
+ * only reserve 3% of free pages by default.
+ */
+static int init_admin_reserve(void)
+{
+ unsigned long free_kbytes;
+
+ free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+ sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
+ return 0;
+}
+module_init(init_admin_reserve)
+
+/*
+ * Reinititalise user and admin reserves if memory is added or removed.
+ *
+ * The default user reserve max is 128MB, and the default max for the
+ * admin reserve is 8MB. These are usually, but not always, enough to
+ * enable recovery from a memory hogging process using login/sshd, a shell,
+ * and tools like top. It may make sense to increase or even disable the
+ * reserve depending on the existence of swap or variations in the recovery
+ * tools. So, the admin may have changed them.
+ *
+ * If memory is added and the reserves have been eliminated or increased above
+ * the default max, then we'll trust the admin.
+ *
+ * If memory is removed and there isn't enough free memory, then we
+ * need to reset the reserves.
+ *
+ * Otherwise keep the reserve set by the admin.
+ */
+static int reserve_mem_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ unsigned long tmp, free_kbytes;
+
+ switch (action) {
+ case MEM_ONLINE:
+ /* Default max is 128MB. Leave alone if modified by operator. */
+ tmp = sysctl_user_reserve_kbytes;
+ if (0 < tmp && tmp < (1UL << 17))
+ init_user_reserve();
+
+ /* Default max is 8MB. Leave alone if modified by operator. */
+ tmp = sysctl_admin_reserve_kbytes;
+ if (0 < tmp && tmp < (1UL << 13))
+ init_admin_reserve();
+
+ break;
+ case MEM_OFFLINE:
+ free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+ if (sysctl_user_reserve_kbytes > free_kbytes) {
+ init_user_reserve();
+ pr_info("vm.user_reserve_kbytes reset to %lu\n",
+ sysctl_user_reserve_kbytes);
+ }
+
+ if (sysctl_admin_reserve_kbytes > free_kbytes) {
+ init_admin_reserve();
+ pr_info("vm.admin_reserve_kbytes reset to %lu\n",
+ sysctl_admin_reserve_kbytes);
+ }
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block reserve_mem_nb = {
+ .notifier_call = reserve_mem_notifier,
+};
+
+static int __meminit init_reserve_notifier(void)
+{
+ if (register_hotmemory_notifier(&reserve_mem_nb))
+ printk("Failed registering memory add/remove notifier for admin reserve");
+
+ return 0;
+}
+module_init(init_reserve_notifier)
projects / ~andy / linux / blobdiff