31 Mar, 2011

1 commit


11 Aug, 2010

1 commit

  • This patch enables hwpoison injection through debug/hwpoison interfaces,
    with which we can test memory error handling for free or reserved
    hugepages (which cannot be tested by madvise() injector).

    [AK: Export PageHuge too for the injection module]
    Signed-off-by: Naoya Horiguchi
    Cc: Andrew Morton
    Acked-by: Fengguang Wu
    Signed-off-by: Andi Kleen

    Naoya Horiguchi
     

16 Dec, 2009

8 commits

  • Signed-off-by: Andi Kleen

    Andi Kleen
     
  • This is a simpler, gentler variant of memory_failure() for soft page
    offlining controlled from user space. It doesn't kill anything, just
    tries to invalidate and if that doesn't work migrate the
    page away.

    This is useful for predictive failure analysis, where a page has
    a high rate of corrected errors, but hasn't gone bad yet. Instead
    it can be offlined early and avoided.

    The offlining is controlled from sysfs, including a new generic
    entry point for hard page offlining for symmetry too.

    We use the page isolate facility to prevent re-allocation
    race. Normally this is only used by memory hotplug. To avoid
    races with memory allocation I am using lock_system_sleep().
    This avoids the situation where memory hotplug is about
    to isolate a page range and then hwpoison undoes that work.
    This is a big hammer currently, but the simplest solution
    currently.

    When the page is not free or LRU we try to free pages
    from slab and other caches. The slab freeing is currently
    quite dumb and does not try to focus on the specific slab
    cache which might own the page. This could be potentially
    improved later.

    Thanks to Fengguang Wu and Haicheng Li for some fixes.

    [Added fix from Andrew Morton to adapt to new migrate_pages prototype]
    Signed-off-by: Andi Kleen

    Andi Kleen
     
  • In some use cases, user doesn't need extra filtering. E.g. user program
    can inject errors through madvise syscall to its own pages, however it
    might not know what the page state exactly is or which inode the page
    belongs to.

    So introduce an one-off interface "corrupt-filter-enable".

    Echo 0 to switch off page filters, and echo 1 to switch on the filters.
    [AK: changed default to 0]

    Signed-off-by: Haicheng Li
    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Haicheng Li
     
  • The hwpoison test suite need to inject hwpoison to a collection of
    selected task pages, and must not touch pages not owned by them and
    thus kill important system processes such as init. (But it's OK to
    mis-hwpoison free/unowned pages as well as shared clean pages.
    Mis-hwpoison of shared dirty pages will kill all tasks, so the test
    suite will target all or non of such tasks in the first place.)

    The memory cgroup serves this purpose well. We can put the target
    processes under the control of a memory cgroup, and tell the hwpoison
    injection code to only kill pages associated with some active memory
    cgroup.

    The prerequisite for doing hwpoison stress tests with mem_cgroup is,
    the mem_cgroup code tracks task pages _accurately_ (unless page is
    locked). Which we believe is/should be true.

    The benefits are simplification of hwpoison injector code. Also the
    mem_cgroup code will automatically be tested by hwpoison test cases.

    The alternative interfaces pin-pfn/unpin-pfn can also delegate the
    (process and page flags) filtering functions reliably to user space.
    However prototype implementation shows that this scheme adds more
    complexity than we wanted.

    Example test case:

    mkdir /cgroup/hwpoison

    usemem -m 100 -s 1000 &
    echo `jobs -p` > /cgroup/hwpoison/tasks

    memcg_ino=$(ls -id /cgroup/hwpoison | cut -f1 -d' ')
    echo $memcg_ino > /debug/hwpoison/corrupt-filter-memcg

    page-types -p `pidof init` --hwpoison # shall do nothing
    page-types -p `pidof usemem` --hwpoison # poison its pages

    [AK: Fix documentation]
    [Add fix for problem noticed by Li Zefan ;
    dentry in the css could be NULL]

    CC: KOSAKI Motohiro
    CC: Hugh Dickins
    CC: Daisuke Nishimura
    CC: Balbir Singh
    CC: KAMEZAWA Hiroyuki
    CC: Li Zefan
    CC: Paul Menage
    CC: Nick Piggin
    CC: Andi Kleen
    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Andi Kleen
     
  • When specified, only poison pages if ((page_flags & mask) == value).

    - corrupt-filter-flags-mask
    - corrupt-filter-flags-value

    This allows stress testing of many kinds of pages.

    Strictly speaking, the buddy pages requires taking zone lock, to avoid
    setting PG_hwpoison on a "was buddy but now allocated to someone" page.
    However we can just do nothing because we set PG_locked in the beginning,
    this prevents the page allocator from allocating it to someone. (It will
    BUG() on the unexpected PG_locked, which is fine for hwpoison testing.)

    [AK: Add select PROC_PAGE_MONITOR to satisfy dependency]

    CC: Nick Piggin
    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Wu Fengguang
     
  • __memory_failure()'s workflow is

    set PG_hwpoison
    //...
    unset PG_hwpoison if didn't pass hwpoison filter

    That could kill unrelated process if it happens to page fault on the
    page with the (temporary) PG_hwpoison. The race should be big enough to
    appear in stress tests.

    Fix it by grabbing the page and checking filter at inject time. This
    also avoids the very noisy "Injecting memory failure..." messages.

    - we don't touch madvise() based injection, because the filters are
    generally not necessary for it.
    - if we want to apply the filters to h/w aided injection, we'd better to
    rearrange the logic in __memory_failure() instead of this patch.

    AK: fix documentation, use drain all, cleanups

    CC: Haicheng Li
    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Wu Fengguang
     
  • Filesystem data/metadata present the most tricky-to-isolate pages.
    It requires careful code review and stress testing to get them right.

    The fs/device filter helps to target the stress tests to some specific
    filesystem pages. The filter condition is block device's major/minor
    numbers:
    - corrupt-filter-dev-major
    - corrupt-filter-dev-minor
    When specified (non -1), only page cache pages that belong to that
    device will be poisoned.

    The filters are checked reliably on the locked and refcounted page.

    Haicheng: clear PG_hwpoison and drop bad page count if filter not OK
    AK: Add documentation

    CC: Haicheng Li
    CC: Nick Piggin
    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Wu Fengguang
     
  • The unpoisoning interface is useful for stress testing tools to
    reclaim poisoned pages (to prevent OOM)

    There is no hardware level unpoisioning, so this
    cannot be used for real memory errors, only for software injected errors.

    Note that it may leak pages silently - those who have been removed from
    LRU cache, but not isolated from page cache/swap cache at hwpoison time.
    Especially the stress test of dirty swap cache pages shall reboot system
    before exhausting memory.

    AK: Fix comments, add documentation, add printks, rename symbol

    Signed-off-by: Wu Fengguang
    Signed-off-by: Andi Kleen

    Wu Fengguang
     

16 Sep, 2009

1 commit