linux/mm/debug.c, branch v4.0

mm: account pmd page tables to the process

2015-02-12T01:06:04Z

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 #include #include #include #include #include #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 Reported-by: Dave Hansen Cc: Hugh Dickins Reviewed-by: Cyrill Gorcunov Cc: Pavel Emelyanov Cc: David Rientjes Tested-by: Sedat Dilek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove rest usage of VM_NONLINEAR and pte_file()

2015-02-10T22:30:31Z

One bit in ->vm_flags is unused now! Signed-off-by: Kirill A. Shutemov Cc: Dan Carpenter Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: move page->mem_cgroup bad page handling into generic code

2014-12-11T01:41:09Z

Now that the external page_cgroup data structure and its lookup is gone, let the generic bad_page() check for page->mem_cgroup sanity. Signed-off-by: Johannes Weiner Acked-by: Michal Hocko Acked-by: Vladimir Davydov Acked-by: David S. Miller Cc: KAMEZAWA Hiroyuki Cc: "Kirill A. Shutemov" Cc: Tejun Heo Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/debug.c: use pr_emerg()

2014-10-10T02:25:59Z

- s/KERN_ALERT/pr_emerg/: we're going BUG so let's maximize the changes of getting the message out. - convert debug.c to pr_foo() Cc: Sasha Levin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: introduce VM_BUG_ON_MM

2014-10-10T02:25:58Z

Very similar to VM_BUG_ON_PAGE and VM_BUG_ON_VMA, dump struct_mm when the bug is hit. [akpm@linux-foundation.org: coding-style fixes] [mhocko@suse.cz: fix build] [mhocko@suse.cz: fix build some more] [akpm@linux-foundation.org: do strange things to avoid doing strange things for the comma separators] Signed-off-by: Sasha Levin Cc: Dave Jones Signed-off-by: Michal Hocko Cc: Valdis Kletnieks Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: move debug code out of page_alloc.c

2014-10-10T02:25:58Z

dump_page() and dump_vma() are not specific to page_alloc.c, move them out so page_alloc.c won't turn into the unofficial debug repository. Signed-off-by: Sasha Levin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds