diff options
author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2015-02-11 18:26:50 -0500 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-11 20:06:04 -0500 |
commit | dc6c9a35b66b520cf67e05d8ca60ebecad3b0479 (patch) | |
tree | 41075776145d02727c15c27d522b4c93529cca77 /mm/debug.c | |
parent | 8aa76875dc15b2dd21fa74eb7c12dc3c75f4b6b6 (diff) |
mm: account pmd page tables to the process
Dave noticed that unprivileged process can allocate significant amount of
memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and
memory cgroup. The trick is to allocate a lot of PMD page tables. Linux
kernel doesn't account PMD tables to the process, only PTE.
The use-cases below use few tricks to allocate a lot of PMD page tables
while keeping VmRSS and VmPTE low. oom_score for the process will be 0.
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#define PUD_SIZE (1UL << 30)
#define PMD_SIZE (1UL << 21)
#define NR_PUD 130000
int main(void)
{
char *addr = NULL;
unsigned long i;
prctl(PR_SET_THP_DISABLE);
for (i = 0; i < NR_PUD ; i++) {
addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
if (addr == MAP_FAILED) {
perror("mmap");
break;
}
*addr = 'x';
munmap(addr, PMD_SIZE);
mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ,
MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0);
if (addr == MAP_FAILED)
perror("re-mmap"), exit(1);
}
printf("PID %d consumed %lu KiB in PMD page tables\n",
getpid(), i * 4096 >> 10);
return pause();
}
The patch addresses the issue by account PMD tables to the process the
same way we account PTE.
The main place where PMD tables is accounted is __pmd_alloc() and
free_pmd_range(). But there're few corner cases:
- HugeTLB can share PMD page tables. The patch handles by accounting
the table to all processes who share it.
- x86 PAE pre-allocates few PMD tables on fork.
- Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity
check on exit(2).
Accounting only happens on configuration where PMD page table's level is
present (PMD is not folded). As with nr_ptes we use per-mm counter. The
counter value is used to calculate baseline for badness score by
oom-killer.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: David Rientjes <rientjes@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/debug.c')
-rw-r--r-- | mm/debug.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/debug.c b/mm/debug.c index d69cb5a7ba9a..3eb3ac2fcee7 100644 --- a/mm/debug.c +++ b/mm/debug.c | |||
@@ -173,7 +173,7 @@ void dump_mm(const struct mm_struct *mm) | |||
173 | "get_unmapped_area %p\n" | 173 | "get_unmapped_area %p\n" |
174 | #endif | 174 | #endif |
175 | "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n" | 175 | "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n" |
176 | "pgd %p mm_users %d mm_count %d nr_ptes %lu map_count %d\n" | 176 | "pgd %p mm_users %d mm_count %d nr_ptes %lu nr_pmds %lu map_count %d\n" |
177 | "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n" | 177 | "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n" |
178 | "pinned_vm %lx shared_vm %lx exec_vm %lx stack_vm %lx\n" | 178 | "pinned_vm %lx shared_vm %lx exec_vm %lx stack_vm %lx\n" |
179 | "start_code %lx end_code %lx start_data %lx end_data %lx\n" | 179 | "start_code %lx end_code %lx start_data %lx end_data %lx\n" |
@@ -206,6 +206,7 @@ void dump_mm(const struct mm_struct *mm) | |||
206 | mm->pgd, atomic_read(&mm->mm_users), | 206 | mm->pgd, atomic_read(&mm->mm_users), |
207 | atomic_read(&mm->mm_count), | 207 | atomic_read(&mm->mm_count), |
208 | atomic_long_read((atomic_long_t *)&mm->nr_ptes), | 208 | atomic_long_read((atomic_long_t *)&mm->nr_ptes), |
209 | mm_nr_pmds((struct mm_struct *)mm), | ||
209 | mm->map_count, | 210 | mm->map_count, |
210 | mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm, | 211 | mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm, |
211 | mm->pinned_vm, mm->shared_vm, mm->exec_vm, mm->stack_vm, | 212 | mm->pinned_vm, mm->shared_vm, mm->exec_vm, mm->stack_vm, |