27 Oct, 2010

40 commits

  • Ensure kmap_atomic() usage is strictly nested

    Signed-off-by: Peter Zijlstra
    Reviewed-by: Rik van Riel
    Acked-by: Chris Metcalf
    Cc: David Howells
    Cc: Hugh Dickins
    Cc: Ingo Molnar
    Cc: Thomas Gleixner
    Cc: "H. Peter Anvin"
    Cc: Steven Rostedt
    Cc: Russell King
    Cc: Ralf Baechle
    Cc: David Miller
    Cc: Paul Mackerras
    Cc: Benjamin Herrenschmidt
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Peter Zijlstra
     
  • When a page has PG_referenced, shrink_page_list() discards it only if it
    is not dirty. This rule works fine if the backing filesystem is a regular
    one. PG_dirty is a good signal that the page was used recently because
    the flusher threads clean pages periodically. In addition, page writeback
    is costlier than simple page discard.

    However, when a page is on tmpfs this heuristic doesn't work because
    flusher threads don't write back tmpfs pages. Consequently tmpfs pages
    always rotate around the lru twice at least and adds unnecessary lru
    churn. Simple tmpfs streaming io shouldn't cause large anonymous page
    swap-out.

    Remove this unncessary reclaim bonus of tmpfs pages.

    Signed-off-by: KOSAKI Motohiro
    Cc: Hugh Dickins
    Reviewed-by: Johannes Weiner
    Reviewed-by: Rik van Riel
    Cc: Minchan Kim
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KOSAKI Motohiro
     
  • The dirty_ratio was silently limited in global_dirty_limits() to >= 5%.
    This is not a user expected behavior. And it's inconsistent with
    calc_period_shift(), which uses the plain vm_dirty_ratio value.

    Let's remove the internal bound.

    At the same time, fix balance_dirty_pages() to work with the
    dirty_thresh=0 case. This allows applications to proceed when
    dirty+writeback pages are all cleaned.

    And ">" fits with the name "exceeded" better than ">=" does. Neil thinks
    it is an aesthetic improvement as well as a functional one :)

    Signed-off-by: Wu Fengguang
    Cc: Jan Kara
    Proposed-by: Con Kolivas
    Acked-by: Peter Zijlstra
    Reviewed-by: Rik van Riel
    Reviewed-by: Neil Brown
    Reviewed-by: KOSAKI Motohiro
    Cc: Michael Rubin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Wu Fengguang
     
  • …r if significant congestion is not being encountered in the current zone

    If congestion_wait() is called with no BDI congested, the caller will
    sleep for the full timeout and this may be an unnecessary sleep. This
    patch adds a wait_iff_congested() that checks congestion and only sleeps
    if a BDI is congested else, it calls cond_resched() to ensure the caller
    is not hogging the CPU longer than its quota but otherwise will not sleep.

    This is aimed at reducing some of the major desktop stalls reported during
    IO. For example, while kswapd is operating, it calls congestion_wait()
    but it could just have been reclaiming clean page cache pages with no
    congestion. Without this patch, it would sleep for a full timeout but
    after this patch, it'll just call schedule() if it has been on the CPU too
    long. Similar logic applies to direct reclaimers that are not making
    enough progress.

    Signed-off-by: Mel Gorman <mel@csn.ul.ie>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Minchan Kim <minchan.kim@gmail.com>
    Cc: Wu Fengguang <fengguang.wu@intel.com>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    Mel Gorman
     
  • isolate_lru_pages() does not just isolate LRU tail pages, but also
    isolates neighbour pages of the eviction page. The neighbour search does
    not stop even if neighbours cannot be isolated which is excessive as the
    lumpy reclaim will no longer result in a successful higher order
    allocation. This patch stops the PFN neighbour pages if an isolation
    fails and moves on to the next block.

    Signed-off-by: KOSAKI Motohiro
    Signed-off-by: Mel Gorman
    Reviewed-by: Wu Fengguang
    Reviewed-by: Minchan Kim
    Reviewed-by: KAMEZAWA Hiroyuki
    Cc: Johannes Weiner
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KOSAKI Motohiro
     
  • After synchrounous lumpy reclaim, the page_list is guaranteed to not have
    active pages as page activation in shrink_page_list() disables lumpy
    reclaim. Remove the dead code.

    Signed-off-by: KOSAKI Motohiro
    Signed-off-by: Mel Gorman
    Reviewed-by: Minchan Kim
    Cc: Johannes Weiner
    Cc: Wu Fengguang
    Cc: Rik van Riel
    Cc: KAMEZAWA Hiroyuki
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KOSAKI Motohiro
     
  • shrink_page_list() can decide to give up reclaiming a page under a
    number of conditions such as

    1. trylock_page() failure
    2. page is unevictable
    3. zone reclaim and page is mapped
    4. PageWriteback() is true
    5. page is swapbacked and swap is full
    6. add_to_swap() failure
    7. page is dirty and gfpmask don't have GFP_IO, GFP_FS
    8. page is pinned
    9. IO queue is congested
    10. pageout() start IO, but not finished

    With lumpy reclaim, failures result in entering synchronous lumpy reclaim
    but this can be unnecessary. In cases (2), (3), (5), (6), (7) and (8),
    there is no point retrying. This patch causes lumpy reclaim to abort when
    it is known it will fail.

    Case (9) is more interesting. current behavior is,
    1. start shrink_page_list(async)
    2. found queue_congested()
    3. skip pageout write
    4. still start shrink_page_list(sync)
    5. wait on a lot of pages
    6. again, found queue_congested()
    7. give up pageout write again

    So, it's useless time wasting. However, just skipping page reclaim is
    also notgood as x86 allocating a huge page needs 512 pages for example.
    It can have more dirty pages than queue congestion threshold (~=128).

    After this patch, pageout() behaves as follows;

    - If order > PAGE_ALLOC_COSTLY_ORDER
    Ignore queue congestion always.
    - If order
    Signed-off-by: Mel Gorman
    Reviewed-by: KAMEZAWA Hiroyuki
    Cc: Johannes Weiner
    Cc: Minchan Kim
    Cc: Wu Fengguang
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KOSAKI Motohiro
     
  • congestion_wait() means "wait until queue congestion is cleared".
    However, synchronous lumpy reclaim does not need this congestion_wait() as
    shrink_page_list(PAGEOUT_IO_SYNC) uses wait_on_page_writeback() and it
    provides the necessary waiting.

    Signed-off-by: KOSAKI Motohiro
    Signed-off-by: Mel Gorman
    Reviewed-by: Minchan Kim
    Reviewed-by: Johannes Weiner
    Reviewed-by: Wu Fengguang
    Reviewed-by: KAMEZAWA Hiroyuki
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KOSAKI Motohiro
     
  • There is strong evidence to indicate a lot of time is being spent in
    congestion_wait(), some of it unnecessarily. This patch adds a tracepoint
    for congestion_wait to record when congestion_wait() was called, how long
    the timeout was for and how long it actually slept.

    Signed-off-by: Mel Gorman
    Reviewed-by: Minchan Kim
    Reviewed-by: Johannes Weiner
    Cc: Wu Fengguang
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mel Gorman
     
  • There have been numerous reports of stalls that pointed at the problem
    being somewhere in the VM. There are multiple roots to the problems which
    means dealing with any of the root problems in isolation is tricky to
    justify on their own and they would still need integration testing. This
    patch series puts together two different patch sets which in combination
    should tackle some of the root causes of latency problems being reported.

    Patch 1 adds a tracepoint for shrink_inactive_list. For this series, the
    most important results is being able to calculate the scanning/reclaim
    ratio as a measure of the amount of work being done by page reclaim.

    Patch 2 accounts for time spent in congestion_wait.

    Patches 3-6 were originally developed by Kosaki Motohiro but reworked for
    this series. It has been noted that lumpy reclaim is far too aggressive
    and trashes the system somewhat. As SLUB uses high-order allocations, a
    large cost incurred by lumpy reclaim will be noticeable. It was also
    reported during transparent hugepage support testing that lumpy reclaim
    was trashing the system and these patches should mitigate that problem
    without disabling lumpy reclaim.

    Patch 7 adds wait_iff_congested() and replaces some callers of
    congestion_wait(). wait_iff_congested() only sleeps if there is a BDI
    that is currently congested. Patch 8 notes that any BDI being congested
    is not necessarily a problem because there could be multiple BDIs of
    varying speeds and numberous zones. It attempts to track when a zone
    being reclaimed contains many pages backed by a congested BDI and if so,
    reclaimers wait on the congestion queue.

    I ran a number of tests with monitoring on X86, X86-64 and PPC64. Each
    machine had 3G of RAM and the CPUs were

    X86: Intel P4 2-core
    X86-64: AMD Phenom 4-core
    PPC64: PPC970MP

    Each used a single disk and the onboard IO controller. Dirty ratio was
    left at 20. I'm just going to report for X86-64 and PPC64 in a vague
    attempt to keep this report short. Four kernels were tested each based on
    v2.6.36-rc4

    traceonly-v2r2: Patches 1 and 2 to instrument vmscan reclaims and congestion_wait
    lowlumpy-v2r3: Patches 1-6 to test if lumpy reclaim is better
    waitcongest-v2r3: Patches 1-7 to only wait on congestion
    waitwriteback-v2r4: Patches 1-8 to detect when a zone is congested

    nocongest-v1r5: Patches 1-3 for testing wait_iff_congestion
    nodirect-v1r5: Patches 1-10 to disable filesystem writeback for better IO

    The tests run were as follows

    kernbench
    compile-based benchmark. Smoke test performance

    sysbench
    OLTP read-only benchmark. Will be re-run in the future as read-write

    micro-mapped-file-stream
    This is a micro-benchmark from Johannes Weiner that accesses a
    large sparse-file through mmap(). It was configured to run in only
    single-CPU mode but can be indicative of how well page reclaim
    identifies suitable pages.

    stress-highalloc
    Tries to allocate huge pages under heavy load.

    kernbench, iozone and sysbench did not report any performance regression
    on any machine. sysbench did pressure the system lightly and there was
    reclaim activity but there were no difference of major interest between
    the kernels.

    X86-64 micro-mapped-file-stream

    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3 waitwriteback-v2r4
    pgalloc_dma 1639.00 ( 0.00%) 667.00 (-145.73%) 1167.00 ( -40.45%) 578.00 (-183.56%)
    pgalloc_dma32 2842410.00 ( 0.00%) 2842626.00 ( 0.01%) 2843043.00 ( 0.02%) 2843014.00 ( 0.02%)
    pgalloc_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgsteal_dma 729.00 ( 0.00%) 85.00 (-757.65%) 609.00 ( -19.70%) 125.00 (-483.20%)
    pgsteal_dma32 2338721.00 ( 0.00%) 2447354.00 ( 4.44%) 2429536.00 ( 3.74%) 2436772.00 ( 4.02%)
    pgsteal_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgscan_kswapd_dma 1469.00 ( 0.00%) 532.00 (-176.13%) 1078.00 ( -36.27%) 220.00 (-567.73%)
    pgscan_kswapd_dma32 4597713.00 ( 0.00%) 4503597.00 ( -2.09%) 4295673.00 ( -7.03%) 3891686.00 ( -18.14%)
    pgscan_kswapd_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgscan_direct_dma 71.00 ( 0.00%) 134.00 ( 47.01%) 243.00 ( 70.78%) 352.00 ( 79.83%)
    pgscan_direct_dma32 305820.00 ( 0.00%) 280204.00 ( -9.14%) 600518.00 ( 49.07%) 957485.00 ( 68.06%)
    pgscan_direct_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pageoutrun 16296.00 ( 0.00%) 21254.00 ( 23.33%) 18447.00 ( 11.66%) 20067.00 ( 18.79%)
    allocstall 443.00 ( 0.00%) 273.00 ( -62.27%) 513.00 ( 13.65%) 1568.00 ( 71.75%)

    These are based on the raw figures taken from /proc/vmstat. It's a rough
    measure of reclaim activity. Note that allocstall counts are higher
    because we are entering direct reclaim more often as a result of not
    sleeping in congestion. In itself, it's not necessarily a bad thing.
    It's easier to get a view of what happened from the vmscan tracepoint
    report.

    FTrace Reclaim Statistics: vmscan

    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3 waitwriteback-v2r4
    Direct reclaims 443 273 513 1568
    Direct reclaim pages scanned 305968 280402 600825 957933
    Direct reclaim pages reclaimed 43503 19005 30327 117191
    Direct reclaim write file async I/O 0 0 0 0
    Direct reclaim write anon async I/O 0 3 4 12
    Direct reclaim write file sync I/O 0 0 0 0
    Direct reclaim write anon sync I/O 0 0 0 0
    Wake kswapd requests 187649 132338 191695 267701
    Kswapd wakeups 3 1 4 1
    Kswapd pages scanned 4599269 4454162 4296815 3891906
    Kswapd pages reclaimed 2295947 2428434 2399818 2319706
    Kswapd reclaim write file async I/O 1 0 1 1
    Kswapd reclaim write anon async I/O 59 187 41 222
    Kswapd reclaim write file sync I/O 0 0 0 0
    Kswapd reclaim write anon sync I/O 0 0 0 0
    Time stalled direct reclaim (seconds) 4.34 2.52 6.63 2.96
    Time kswapd awake (seconds) 11.15 10.25 11.01 10.19

    Total pages scanned 4905237 4734564 4897640 4849839
    Total pages reclaimed 2339450 2447439 2430145 2436897
    %age total pages scanned/reclaimed 47.69% 51.69% 49.62% 50.25%
    %age total pages scanned/written 0.00% 0.00% 0.00% 0.00%
    %age file pages scanned/written 0.00% 0.00% 0.00% 0.00%
    Percentage Time Spent Direct Reclaim 29.23% 19.02% 38.48% 20.25%
    Percentage Time kswapd Awake 78.58% 78.85% 76.83% 79.86%

    What is interesting here for nocongest in particular is that while direct
    reclaim scans more pages, the overall number of pages scanned remains the
    same and the ratio of pages scanned to pages reclaimed is more or less the
    same. In other words, while we are sleeping less, reclaim is not doing
    more work and as direct reclaim and kswapd is awake for less time, it
    would appear to be doing less work.

    FTrace Reclaim Statistics: congestion_wait
    Direct number congest waited 87 196 64 0
    Direct time congest waited 4604ms 4732ms 5420ms 0ms
    Direct full congest waited 72 145 53 0
    Direct number conditional waited 0 0 324 1315
    Direct time conditional waited 0ms 0ms 0ms 0ms
    Direct full conditional waited 0 0 0 0
    KSwapd number congest waited 20 10 15 7
    KSwapd time congest waited 1264ms 536ms 884ms 284ms
    KSwapd full congest waited 10 4 6 2
    KSwapd number conditional waited 0 0 0 0
    KSwapd time conditional waited 0ms 0ms 0ms 0ms
    KSwapd full conditional waited 0 0 0 0

    The vanilla kernel spent 8 seconds asleep in direct reclaim and no time at
    all asleep with the patches.

    MMTests Statistics: duration
    User/Sys Time Running Test (seconds) 10.51 10.73 10.6 11.66
    Total Elapsed Time (seconds) 14.19 13.00 14.33 12.76

    Overall, the tests completed faster. It is interesting to note that backing off further
    when a zone is congested and not just a BDI was more efficient overall.

    PPC64 micro-mapped-file-stream
    pgalloc_dma 3024660.00 ( 0.00%) 3027185.00 ( 0.08%) 3025845.00 ( 0.04%) 3026281.00 ( 0.05%)
    pgalloc_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgsteal_dma 2508073.00 ( 0.00%) 2565351.00 ( 2.23%) 2463577.00 ( -1.81%) 2532263.00 ( 0.96%)
    pgsteal_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgscan_kswapd_dma 4601307.00 ( 0.00%) 4128076.00 ( -11.46%) 3912317.00 ( -17.61%) 3377165.00 ( -36.25%)
    pgscan_kswapd_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pgscan_direct_dma 629825.00 ( 0.00%) 971622.00 ( 35.18%) 1063938.00 ( 40.80%) 1711935.00 ( 63.21%)
    pgscan_direct_normal 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%) 0.00 ( 0.00%)
    pageoutrun 27776.00 ( 0.00%) 20458.00 ( -35.77%) 18763.00 ( -48.04%) 18157.00 ( -52.98%)
    allocstall 977.00 ( 0.00%) 2751.00 ( 64.49%) 2098.00 ( 53.43%) 5136.00 ( 80.98%)

    Similar trends to x86-64. allocstalls are up but it's not necessarily bad.

    FTrace Reclaim Statistics: vmscan
    Direct reclaims 977 2709 2098 5136
    Direct reclaim pages scanned 629825 963814 1063938 1711935
    Direct reclaim pages reclaimed 75550 242538 150904 387647
    Direct reclaim write file async I/O 0 0 0 2
    Direct reclaim write anon async I/O 0 10 0 4
    Direct reclaim write file sync I/O 0 0 0 0
    Direct reclaim write anon sync I/O 0 0 0 0
    Wake kswapd requests 392119 1201712 571935 571921
    Kswapd wakeups 3 2 3 3
    Kswapd pages scanned 4601307 4128076 3912317 3377165
    Kswapd pages reclaimed 2432523 2318797 2312673 2144616
    Kswapd reclaim write file async I/O 20 1 1 1
    Kswapd reclaim write anon async I/O 57 132 11 121
    Kswapd reclaim write file sync I/O 0 0 0 0
    Kswapd reclaim write anon sync I/O 0 0 0 0
    Time stalled direct reclaim (seconds) 6.19 7.30 13.04 10.88
    Time kswapd awake (seconds) 21.73 26.51 25.55 23.90

    Total pages scanned 5231132 5091890 4976255 5089100
    Total pages reclaimed 2508073 2561335 2463577 2532263
    %age total pages scanned/reclaimed 47.95% 50.30% 49.51% 49.76%
    %age total pages scanned/written 0.00% 0.00% 0.00% 0.00%
    %age file pages scanned/written 0.00% 0.00% 0.00% 0.00%
    Percentage Time Spent Direct Reclaim 18.89% 20.65% 32.65% 27.65%
    Percentage Time kswapd Awake 72.39% 80.68% 78.21% 77.40%

    Again, a similar trend that the congestion_wait changes mean that direct
    reclaim scans more pages but the overall number of pages scanned while
    slightly reduced, are very similar. The ratio of scanning/reclaimed
    remains roughly similar. The downside is that kswapd and direct reclaim
    was awake longer and for a larger percentage of the overall workload.
    It's possible there were big differences in the amount of time spent
    reclaiming slab pages between the different kernels which is plausible
    considering that the micro tests runs after fsmark and sysbench.

    Trace Reclaim Statistics: congestion_wait
    Direct number congest waited 845 1312 104 0
    Direct time congest waited 19416ms 26560ms 7544ms 0ms
    Direct full congest waited 745 1105 72 0
    Direct number conditional waited 0 0 1322 2935
    Direct time conditional waited 0ms 0ms 12ms 312ms
    Direct full conditional waited 0 0 0 3
    KSwapd number congest waited 39 102 75 63
    KSwapd time congest waited 2484ms 6760ms 5756ms 3716ms
    KSwapd full congest waited 20 48 46 25
    KSwapd number conditional waited 0 0 0 0
    KSwapd time conditional waited 0ms 0ms 0ms 0ms
    KSwapd full conditional waited 0 0 0 0

    The vanilla kernel spent 20 seconds asleep in direct reclaim and only
    312ms asleep with the patches. The time kswapd spent congest waited was
    also reduced by a large factor.

    MMTests Statistics: duration
    ser/Sys Time Running Test (seconds) 26.58 28.05 26.9 28.47
    Total Elapsed Time (seconds) 30.02 32.86 32.67 30.88

    With all patches applies, the completion times are very similar.

    X86-64 STRESS-HIGHALLOC
    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4
    Pass 1 82.00 ( 0.00%) 84.00 ( 2.00%) 85.00 ( 3.00%) 85.00 ( 3.00%)
    Pass 2 90.00 ( 0.00%) 87.00 (-3.00%) 88.00 (-2.00%) 89.00 (-1.00%)
    At Rest 92.00 ( 0.00%) 90.00 (-2.00%) 90.00 (-2.00%) 91.00 (-1.00%)

    Success figures across the board are broadly similar.

    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4
    Direct reclaims 1045 944 886 887
    Direct reclaim pages scanned 135091 119604 109382 101019
    Direct reclaim pages reclaimed 88599 47535 47863 46671
    Direct reclaim write file async I/O 494 283 465 280
    Direct reclaim write anon async I/O 29357 13710 16656 13462
    Direct reclaim write file sync I/O 154 2 2 3
    Direct reclaim write anon sync I/O 14594 571 509 561
    Wake kswapd requests 7491 933 872 892
    Kswapd wakeups 814 778 731 780
    Kswapd pages scanned 7290822 15341158 11916436 13703442
    Kswapd pages reclaimed 3587336 3142496 3094392 3187151
    Kswapd reclaim write file async I/O 91975 32317 28022 29628
    Kswapd reclaim write anon async I/O 1992022 789307 829745 849769
    Kswapd reclaim write file sync I/O 0 0 0 0
    Kswapd reclaim write anon sync I/O 0 0 0 0
    Time stalled direct reclaim (seconds) 4588.93 2467.16 2495.41 2547.07
    Time kswapd awake (seconds) 2497.66 1020.16 1098.06 1176.82

    Total pages scanned 7425913 15460762 12025818 13804461
    Total pages reclaimed 3675935 3190031 3142255 3233822
    %age total pages scanned/reclaimed 49.50% 20.63% 26.13% 23.43%
    %age total pages scanned/written 28.66% 5.41% 7.28% 6.47%
    %age file pages scanned/written 1.25% 0.21% 0.24% 0.22%
    Percentage Time Spent Direct Reclaim 57.33% 42.15% 42.41% 42.99%
    Percentage Time kswapd Awake 43.56% 27.87% 29.76% 31.25%

    Scanned/reclaimed ratios again look good with big improvements in
    efficiency. The Scanned/written ratios also look much improved. With a
    better scanned/written ration, there is an expectation that IO would be
    more efficient and indeed, the time spent in direct reclaim is much
    reduced by the full series and kswapd spends a little less time awake.

    Overall, indications here are that allocations were happening much faster
    and this can be seen with a graph of the latency figures as the
    allocations were taking place
    http://www.csn.ul.ie/~mel/postings/vmscanreduce-20101509/highalloc-interlatency-hydra-mean.ps

    FTrace Reclaim Statistics: congestion_wait
    Direct number congest waited 1333 204 169 4
    Direct time congest waited 78896ms 8288ms 7260ms 200ms
    Direct full congest waited 756 92 69 2
    Direct number conditional waited 0 0 26 186
    Direct time conditional waited 0ms 0ms 0ms 2504ms
    Direct full conditional waited 0 0 0 25
    KSwapd number congest waited 4 395 227 282
    KSwapd time congest waited 384ms 25136ms 10508ms 18380ms
    KSwapd full congest waited 3 232 98 176
    KSwapd number conditional waited 0 0 0 0
    KSwapd time conditional waited 0ms 0ms 0ms 0ms
    KSwapd full conditional waited 0 0 0 0
    KSwapd full conditional waited 318 0 312 9

    Overall, the time spent speeping is reduced. kswapd is still hitting
    congestion_wait() but that is because there are callers remaining where it
    wasn't clear in advance if they should be changed to wait_iff_congested()
    or not. Overall the sleep imes are reduced though - from 79ish seconds to
    about 19.

    MMTests Statistics: duration
    User/Sys Time Running Test (seconds) 3415.43 3386.65 3388.39 3377.5
    Total Elapsed Time (seconds) 5733.48 3660.33 3689.41 3765.39

    With the full series, the time to complete the tests are reduced by 30%

    PPC64 STRESS-HIGHALLOC
    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4
    Pass 1 17.00 ( 0.00%) 34.00 (17.00%) 38.00 (21.00%) 43.00 (26.00%)
    Pass 2 25.00 ( 0.00%) 37.00 (12.00%) 42.00 (17.00%) 46.00 (21.00%)
    At Rest 49.00 ( 0.00%) 43.00 (-6.00%) 45.00 (-4.00%) 51.00 ( 2.00%)

    Success rates there are *way* up particularly considering that the 16MB
    huge pages on PPC64 mean that it's always much harder to allocate them.

    FTrace Reclaim Statistics: vmscan
    stress-highalloc stress-highalloc stress-highalloc stress-highalloc
    traceonly-v2r2 lowlumpy-v2r3 waitcongest-v2r3waitwriteback-v2r4
    Direct reclaims 499 505 564 509
    Direct reclaim pages scanned 223478 41898 51818 45605
    Direct reclaim pages reclaimed 137730 21148 27161 23455
    Direct reclaim write file async I/O 399 136 162 136
    Direct reclaim write anon async I/O 46977 2865 4686 3998
    Direct reclaim write file sync I/O 29 0 1 3
    Direct reclaim write anon sync I/O 31023 159 237 239
    Wake kswapd requests 420 351 360 326
    Kswapd wakeups 185 294 249 277
    Kswapd pages scanned 15703488 16392500 17821724 17598737
    Kswapd pages reclaimed 5808466 2908858 3139386 3145435
    Kswapd reclaim write file async I/O 159938 18400 18717 13473
    Kswapd reclaim write anon async I/O 3467554 228957 322799 234278
    Kswapd reclaim write file sync I/O 0 0 0 0
    Kswapd reclaim write anon sync I/O 0 0 0 0
    Time stalled direct reclaim (seconds) 9665.35 1707.81 2374.32 1871.23
    Time kswapd awake (seconds) 9401.21 1367.86 1951.75 1328.88

    Total pages scanned 15926966 16434398 17873542 17644342
    Total pages reclaimed 5946196 2930006 3166547 3168890
    %age total pages scanned/reclaimed 37.33% 17.83% 17.72% 17.96%
    %age total pages scanned/written 23.27% 1.52% 1.94% 1.43%
    %age file pages scanned/written 1.01% 0.11% 0.11% 0.08%
    Percentage Time Spent Direct Reclaim 44.55% 35.10% 41.42% 36.91%
    Percentage Time kswapd Awake 86.71% 43.58% 52.67% 41.14%

    While the scanning rates are slightly up, the scanned/reclaimed and
    scanned/written figures are much improved. The time spent in direct
    reclaim and with kswapd are massively reduced, mostly by the lowlumpy
    patches.

    FTrace Reclaim Statistics: congestion_wait
    Direct number congest waited 725 303 126 3
    Direct time congest waited 45524ms 9180ms 5936ms 300ms
    Direct full congest waited 487 190 52 3
    Direct number conditional waited 0 0 200 301
    Direct time conditional waited 0ms 0ms 0ms 1904ms
    Direct full conditional waited 0 0 0 19
    KSwapd number congest waited 0 2 23 4
    KSwapd time congest waited 0ms 200ms 420ms 404ms
    KSwapd full congest waited 0 2 2 4
    KSwapd number conditional waited 0 0 0 0
    KSwapd time conditional waited 0ms 0ms 0ms 0ms
    KSwapd full conditional waited 0 0 0 0

    Not as dramatic a story here but the time spent asleep is reduced and we
    can still see what wait_iff_congested is going to sleep when necessary.

    MMTests Statistics: duration
    User/Sys Time Running Test (seconds) 12028.09 3157.17 3357.79 3199.16
    Total Elapsed Time (seconds) 10842.07 3138.72 3705.54 3229.85

    The time to complete this test goes way down. With the full series, we
    are allocating over twice the number of huge pages in 30% of the time and
    there is a corresponding impact on the allocation latency graph available
    at.

    http://www.csn.ul.ie/~mel/postings/vmscanreduce-20101509/highalloc-interlatency-powyah-mean.ps

    This patch:

    Add a trace event for shrink_inactive_list() and updates the sample
    postprocessing script appropriately. It can be used to determine how many
    pages were reclaimed and for non-lumpy reclaim where exactly the pages
    were reclaimed from.

    Signed-off-by: Mel Gorman
    Cc: Johannes Weiner
    Cc: Minchan Kim
    Cc: Wu Fengguang
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mel Gorman
     
  • `priority' cannot be negative here. And the comment is obsolete.

    Signed-off-by: Shaohua Li
    Reviewed-by: KOSAKI Motohiro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Shaohua Li
     
  • NODE_NOT_IN_PAGE_FLAGS is defined in mm.h when the node information is not
    stored in the page flags bitmap.

    Unfortunately, there's a typo in one of the checks for it. This patch
    fixes it (s/NODE_NOT_IN_PAGEFLAGS/NODE_NOT_IN_PAGE_FLAGS/). Since this
    has been around for ages, I doubt it's been causing any serious problems.

    Signed-off-by: Will Deacon
    Cc: Christoph Lameter
    Cc: Mel Gorman
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Will Deacon
     
  • The kernel already exposes the user desired thresholds in /proc/sys/vm
    with dirty_background_ratio and background_ratio. But the kernel may
    alter the number requested without giving the user any indication that is
    the case.

    Knowing the actual ratios the kernel is honoring can help app developers
    understand how their buffered IO will be sent to the disk.

    $ grep threshold /proc/vmstat
    nr_dirty_threshold 409111
    nr_dirty_background_threshold 818223

    Signed-off-by: Michael Rubin
    Cc: Wu Fengguang
    Cc: Dave Chinner
    Cc: Jens Axboe
    Cc: KOSAKI Motohiro
    Cc: Nick Piggin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Michael Rubin
     
  • For NUMA node systems it is important to have visibility in memory
    characteristics. Two of the /proc/vmstat values "nr_written" and
    "nr_dirtied" are added here.

    # cat /sys/devices/system/node/node20/vmstat
    nr_written 0
    nr_dirtied 0

    Signed-off-by: Michael Rubin
    Reviewed-by: Wu Fengguang
    Cc: Dave Chinner
    Cc: Jens Axboe
    Cc: KOSAKI Motohiro
    Cc: Nick Piggin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Michael Rubin
     
  • To help developers and applications gain visibility into writeback
    behaviour adding two entries to vm_stat_items and /proc/vmstat. This will
    allow us to track the "written" and "dirtied" counts.

    # grep nr_dirtied /proc/vmstat
    nr_dirtied 3747
    # grep nr_written /proc/vmstat
    nr_written 3618

    Signed-off-by: Michael Rubin
    Reviewed-by: Wu Fengguang
    Cc: Dave Chinner
    Cc: Jens Axboe
    Cc: KOSAKI Motohiro
    Cc: Nick Piggin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Michael Rubin
     
  • To help developers and applications gain visibility into writeback
    behaviour this patch adds two counters to /proc/vmstat.

    # grep nr_dirtied /proc/vmstat
    nr_dirtied 3747
    # grep nr_written /proc/vmstat
    nr_written 3618

    These entries allow user apps to understand writeback behaviour over time
    and learn how it is impacting their performance. Currently there is no
    way to inspect dirty and writeback speed over time. It's not possible for
    nr_dirty/nr_writeback.

    These entries are necessary to give visibility into writeback behaviour.
    We have /proc/diskstats which lets us understand the io in the block
    layer. We have blktrace for more in depth understanding. We have
    e2fsprogs and debugsfs to give insight into the file systems behaviour,
    but we don't offer our users the ability understand what writeback is
    doing. There is no way to know how active it is over the whole system, if
    it's falling behind or to quantify it's efforts. With these values
    exported users can easily see how much data applications are sending
    through writeback and also at what rates writeback is processing this
    data. Comparing the rates of change between the two allow developers to
    see when writeback is not able to keep up with incoming traffic and the
    rate of dirty memory being sent to the IO back end. This allows folks to
    understand their io workloads and track kernel issues. Non kernel
    engineers at Google often use these counters to solve puzzling performance
    problems.

    Patch #4 adds a pernode vmstat file with nr_dirtied and nr_written

    Patch #5 add writeback thresholds to /proc/vmstat

    Currently these values are in debugfs. But they should be promoted to
    /proc since they are useful for developers who are writing databases
    and file servers and are not debugging the kernel.

    The output is as below:

    # grep threshold /proc/vmstat
    nr_pages_dirty_threshold 409111
    nr_pages_dirty_background_threshold 818223

    This patch:

    This allows code outside of the mm core to safely manipulate page
    writeback state and not worry about the other accounting. Not using these
    routines means that some code will lose track of the accounting and we get
    bugs.

    Modify nilfs2 to use interface.

    Signed-off-by: Michael Rubin
    Reviewed-by: KOSAKI Motohiro
    Reviewed-by: Wu Fengguang
    Cc: KONISHI Ryusuke
    Cc: Jiro SEKIBA
    Cc: Dave Chinner
    Cc: Jens Axboe
    Cc: KOSAKI Motohiro
    Cc: Nick Piggin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Michael Rubin
     
  • Function check_range may return ERR_PTR(...). Check for it.

    Signed-off-by: Vasiliy Kulikov
    Acked-by: David Rientjes
    Reviewed-by: Christoph Lameter
    Reviewed-by: KOSAKI Motohiro
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Vasiliy Kulikov
     
  • Ying Han reported that backing aging of anon pages in no swap system
    causes unnecessary TLB flush.

    When I sent a patch(69c8548175), I wanted this patch but Rik pointed out
    and allowed aging of anon pages to give a chance to promote from inactive
    to active LRU.

    It has a two problem.

    1) non-swap system

    Never make sense to age anon pages.

    2) swap configured but still doesn't swapon

    It doesn't make sense to age anon pages until swap-on time. But it's
    arguable. If we have aged anon pages by swapon, VM have moved anon pages
    from active to inactive. And in the time swapon by admin, the VM can't
    reclaim hot pages so we can protect hot pages swapout.

    But let's think about it. When does swap-on happen? It depends on admin.
    we can't expect it. Nonetheless, we have done aging of anon pages to
    protect hot pages swapout. It means we lost run time overhead when below
    high watermark but gain hot page swap-[in/out] overhead when VM decide
    swapout. Is it true? Let's think more detail. We don't promote anon
    pages in case of non-swap system. So even though VM does aging of anon
    pages, the pages would be in inactive LRU for a long time. It means many
    of pages in there would mark access bit again. So access bit hot/code
    separation would be pointless.

    This patch prevents unnecessary anon pages demotion in not-yet-swapon and
    non-configured swap system. Even, in non-configuared swap system
    inactive_anon_is_low can be compiled out.

    It could make side effect that hot anon pages could swap out when admin
    does swap on. But I think sooner or later it would be steady state. So
    it's not a big problem.

    We could lose someting but gain more thing(TLB flush and unnecessary
    function call to demote anon pages).

    Signed-off-by: Ying Han
    Signed-off-by: Minchan Kim
    Reviewed-by: Rik van Riel
    Reviewed-by: KOSAKI Motohiro
    Cc: Johannes Weiner
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Minchan Kim
     
  • Now, sysfs interface of memory hotplug shows whether the section is
    removable or not. But it checks only migrateype of pages and doesn't
    check details of cluster of pages.

    Next, memory hotplug's set_migratetype_isolate() has the same kind of
    check, too.

    This patch adds the function __count_unmovable_pages() and makes above 2
    checks to use the same logic. Then, is_removable and hotremove code uses
    the same logic. No changes in the hotremove logic itself.

    TODO: need to find a way to check RECLAMABLE. But, considering bit,
    calling shrink_slab() against a range before starting memory hotremove
    sounds better. If so, this patch's logic doesn't need to be changed.

    [akpm@linux-foundation.org: coding-style fixes]
    Signed-off-by: KAMEZAWA Hiroyuki
    Reported-by: Michal Hocko
    Cc: Wu Fengguang
    Cc: Mel Gorman
    Cc: KAMEZAWA Hiroyuki
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KAMEZAWA Hiroyuki
     
  • Even if notifier cannot find any pages, it doesn't mean no pages are
    available...And, if there are no notifiers registered, this condition will
    be always true and memory hotplug will show -EBUSY.

    This is a bug but not critical.

    In most case, a pageblock which will be offlined is MIGRATE_MOVABLE This
    "notifier" is called only when the pageblock is _not_ MIGRATE_MOVABLE.
    But if not MIGRATE_MOVABLE, it's common case that memory hotplug will
    fail. So, no one notice this bug.

    Signed-off-by: KAMEZAWA Hiroyuki
    Cc: Michal Hocko
    Cc: Wu Fengguang
    Cc: Mel Gorman
    Cc: KAMEZAWA Hiroyuki
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    KAMEZAWA Hiroyuki
     
  • Presently update_nr_listpages() doesn't have a role. That's because lists
    passed is always empty just after calling migrate_pages. The
    migrate_pages cleans up page list which have failed to migrate before
    returning by aaa994b3.

    [PATCH] page migration: handle freeing of pages in migrate_pages()

    Do not leave pages on the lists passed to migrate_pages(). Seems that we will
    not need any postprocessing of pages. This will simplify the handling of
    pages by the callers of migrate_pages().

    At that time, we thought we don't need any postprocessing of pages. But
    the situation is changed. The compaction need to know the number of
    failed to migrate for COMPACTPAGEFAILED stat

    This patch makes new rule for caller of migrate_pages to call
    putback_lru_pages. So caller need to clean up the lists so it has a
    chance to postprocess the pages. [suggested by Christoph Lameter]

    Signed-off-by: Minchan Kim
    Cc: Hugh Dickins
    Cc: Andi Kleen
    Reviewed-by: Mel Gorman
    Reviewed-by: Wu Fengguang
    Acked-by: Christoph Lameter
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Minchan Kim
     
  • Non-NUMA systems do never create these files anyway, since they are only
    created by driver subsystem when NUMA is configured.

    [akpm@linux-foundation.org: cleanup]
    Signed-off-by: Thadeu Lima de Souza Cascardo
    Reviewed-by: KOSAKI Motohiro
    Cc: Lee Schermerhorn
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Thadeu Lima de Souza Cascardo
     
  • The presently-unused macro was missing one parameter.

    Signed-off-by: zeal
    Acked-by: Mel Gorman
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    zeal
     
  • This removes more dead code that was somehow missed by commit 0d99519efef
    (writeback: remove unused nonblocking and congestion checks). There are
    no behavior change except for the removal of two entries from one of the
    ext4 tracing interface.

    The nonblocking checks in ->writepages are no longer used because the
    flusher now prefer to block on get_request_wait() than to skip inodes on
    IO congestion. The latter will lead to more seeky IO.

    The nonblocking checks in ->writepage are no longer used because it's
    redundant with the WB_SYNC_NONE check.

    We no long set ->nonblocking in VM page out and page migration, because
    a) it's effectively redundant with WB_SYNC_NONE in current code
    b) it's old semantic of "Don't get stuck on request queues" is mis-behavior:
    that would skip some dirty inodes on congestion and page out others, which
    is unfair in terms of LRU age.

    Inspired by Christoph Hellwig. Thanks!

    Signed-off-by: Wu Fengguang
    Cc: Theodore Ts'o
    Cc: David Howells
    Cc: Sage Weil
    Cc: Steve French
    Cc: Chris Mason
    Cc: Jens Axboe
    Cc: Christoph Hellwig
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Wu Fengguang
     
  • The locking order in oom_adjust_write() and oom_score_adj_write() for
    task->alloc_lock and task->sighand->siglock is reversed, and lockdep
    notices that irqs could encounter an ABBA scenario.

    This fixes the locking order so that we always take task_lock(task) prior
    to lock_task_sighand(task).

    Signed-off-by: David Rientjes
    Reported-by: Andrew Morton
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Cc: Ying Han
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    David Rientjes
     
  • It's better to use proper error handling in oom_adjust_write() and
    oom_score_adj_write() instead of duplicating the locking order on various
    exit paths.

    Suggested-by: Andrew Morton
    Signed-off-by: David Rientjes
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Cc: Ying Han
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    David Rientjes
     
  • It's necessary to kill all threads that share an oom killed task's mm if
    the goal is to lead to future memory freeing.

    This patch reintroduces the code removed in 8c5cd6f3 (oom: oom_kill
    doesn't kill vfork parent (or child)) since it is obsoleted.

    It's now guaranteed that any task passed to oom_kill_task() does not share
    an mm with any thread that is unkillable. Thus, we're safe to issue a
    SIGKILL to any thread sharing the same mm.

    This is especially necessary to solve an mm->mmap_sem livelock issue
    whereas an oom killed thread must acquire the lock in the exit path while
    another thread is holding it in the page allocator while trying to
    allocate memory itself (and will preempt the oom killer since a task was
    already killed). Since tasks with pending fatal signals are now granted
    access to memory reserves, the thread holding the lock may quickly
    allocate and release the lock so that the oom killed task may exit.

    This mainly is for threads that are cloned with CLONE_VM but not
    CLONE_THREAD, so they are in a different thread group. Non-NPTL threads
    exist in the wild and this change is necessary to prevent the livelock in
    such cases. We care more about preventing the livelock than incurring the
    additional tasklist in the oom killer when a task has been killed.
    Systems that are sufficiently large to not want the tasklist scan in the
    oom killer in the first place already have the option of enabling
    /proc/sys/vm/oom_kill_allocating_task, which was designed specifically for
    that purpose.

    This code had existed in the oom killer for over eight years dating back
    to the 2.4 kernel.

    [akpm@linux-foundation.org: add nice comment]
    Signed-off-by: David Rientjes
    Acked-by: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Cc: Ying Han
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    David Rientjes
     
  • The oom killer's goal is to kill a memory-hogging task so that it may
    exit, free its memory, and allow the current context to allocate the
    memory that triggered it in the first place. Thus, killing a task is
    pointless if other threads sharing its mm cannot be killed because of its
    /proc/pid/oom_adj or /proc/pid/oom_score_adj value.

    This patch checks whether any other thread sharing p->mm has an
    oom_score_adj of OOM_SCORE_ADJ_MIN. If so, the thread cannot be killed
    and oom_badness(p) returns 0, meaning it's unkillable.

    Signed-off-by: David Rientjes
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Cc: Ying Han
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    David Rientjes
     
  • It's pointless to kill a task if another thread sharing its mm cannot be
    killed to allow future memory freeing. A subsequent patch will prevent
    kills in such cases, but first it's necessary to have a way to flag a task
    that shares memory with an OOM_DISABLE task that doesn't incur an
    additional tasklist scan, which would make select_bad_process() an O(n^2)
    function.

    This patch adds an atomic counter to struct mm_struct that follows how
    many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN.
    They cannot be killed by the kernel, so their memory cannot be freed in
    oom conditions.

    This only requires task_lock() on the task that we're operating on, it
    does not require mm->mmap_sem since task_lock() pins the mm and the
    operation is atomic.

    [rientjes@google.com: changelog and sys_unshare() code]
    [rientjes@google.com: protect oom_disable_count with task_lock in fork]
    [rientjes@google.com: use old_mm for oom_disable_count in exec]
    Signed-off-by: Ying Han
    Signed-off-by: David Rientjes
    Cc: KAMEZAWA Hiroyuki
    Cc: KOSAKI Motohiro
    Cc: Rik van Riel
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ying Han
     
  • Signed-off-by: Matt Mackall
    Cc: Nikanth Karthikesan
    Cc: Balbir Singh
    Cc: Wu Fengguang
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Matt Mackall
     
  • We use vmcore in our production kernel for a long time, it is pretty
    stable now. So I don't think we need to mark it as experimental any more.

    Signed-off-by: WANG Cong
    Acked-by: Neil Horman
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    WANG Cong
     
  • Commit df9ee292 ("Fix IRQ flag handling naming") changed the IRQ flag
    handling naming scheme and broke UML:

    In file included from arch/um/include/asm/fixmap.h:5,
    from arch/um/include/shared/um_uaccess.h:10,
    from arch/um/include/asm/uaccess.h:41,
    from arch/um/include/asm/thread_info.h:13,
    from include/linux/thread_info.h:56,
    from include/linux/preempt.h:9,
    from include/linux/spinlock.h:50,
    from include/linux/seqlock.h:29,
    from include/linux/time.h:8,
    from include/linux/stat.h:60,
    from include/linux/module.h:10,
    from init/main.c:13:
    arch/um/include/asm/system.h:11:1: warning: "local_save_flags" redefined

    This patch brings the new scheme to UML and makes it work again.

    Signed-off-by: Richard Weinberger
    Acked-by: David Howells
    Cc: Jeff Dike
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Richard Weinberger
     
  • WARNING: at lib/list_debug.c:26 __list_add+0x3f/0x81()
    Hardware name: Express5800/B120a [N8400-085]
    list_add corruption. next->prev should be prev (ffffffff81a7ea00), but was dead000000200200. (next=ffff88080b872d58).
    Modules linked in: aoe ipt_MASQUERADE iptable_nat nf_nat autofs4 sunrpc bridge 8021q garp stp llc ipv6 cpufreq_ondemand acpi_cpufreq freq_table dm_round_robin dm_multipath kvm_intel kvm uinput lpfc scsi_transport_fc igb ioatdma scsi_tgt i2c_i801 i2c_core dca iTCO_wdt iTCO_vendor_support pcspkr shpchp megaraid_sas [last unloaded: aoe]
    Pid: 54, comm: events/3 Tainted: G W 2.6.34-vanilla1 #1
    Call Trace:
    [] warn_slowpath_common+0x7c/0x94
    [] warn_slowpath_fmt+0x41/0x43
    [] __list_add+0x3f/0x81
    [] __percpu_counter_init+0x59/0x6b
    [] bdi_init+0x118/0x17e
    [] blk_alloc_queue_node+0x79/0x143
    [] blk_alloc_queue+0x11/0x13
    [] aoeblk_gdalloc+0x8e/0x1c9 [aoe]
    [] aoecmd_sleepwork+0x25/0xa8 [aoe]
    [] worker_thread+0x1a9/0x237
    [] ? aoecmd_sleepwork+0x0/0xa8 [aoe]
    [] ? autoremove_wake_function+0x0/0x39
    [] ? worker_thread+0x0/0x237
    [] kthread+0x7f/0x87
    [] kernel_thread_helper+0x4/0x10
    [] ? kthread+0x0/0x87
    [] ? kernel_thread_helper+0x0/0x10

    It's because there is no initialization code for a list_head contained in
    the struct backing_dev_info under CONFIG_HOTPLUG_CPU, and the bug comes up
    when block device drivers calling blk_alloc_queue() are used. In case of
    me, I got them by using aoe.

    Signed-off-by: Masanori Itoh
    Cc: Tejun Heo
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Masanori ITOH
     
  • This helper is wrong: it coerces signed values into unsigned ones, so code
    such as

    if (kfifo_alloc(...) < 0) {
    error
    }

    will fail to detect the error.

    So let's disable __kfifo_must_check_helper() for 2.6.36.

    Cc: Randy Dunlap
    Cc: Stefani Seibold
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrew Morton
     
  • 365b1818 ("add f_flags to struct statfs(64)") resized f_spare within
    struct statfs which caused a UML crash. There is no need to copy f_spare.

    Signed-off-by: Richard Weinberger
    Reported-by: Toralf Förster
    Tested-by: Toralf Förster
    Cc: Christoph Hellwig
    Cc: Al Viro
    Cc: Jeff Dike
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Richard Weinberger
     
  • Unloading ipmi module can trigger following error. (if
    CONFIG_DEBUG_SPINLOCK=y)

    [ 9633.779590] BUG: spinlock bad magic on CPU#1, rmmod/7170
    [ 9633.779606] lock: f41f5414, .magic: 00000000, .owner:
    /-1, .owner_cpu: 0
    [ 9633.779626] Pid: 7170, comm: rmmod Not tainted
    2.6.36-rc7-11474-gb71eb1e-dirty #328
    [ 9633.779644] Call Trace:
    [ 9633.779657] [] ? printk+0x18/0x1c
    [ 9633.779672] [] spin_bug+0xa3/0xf0
    [ 9633.779685] [] do_raw_spin_lock+0x7d/0x160
    [ 9633.779702] [] ? release_sysfs_dirent+0x47/0xb0
    [ 9633.779718] [] ? sysfs_addrm_finish+0xa8/0xd0
    [ 9633.779734] [] _raw_spin_lock_irqsave+0xc/0x20
    [ 9633.779752] [] cleanup_one_si+0x6a/0x200 [ipmi_si]
    [ 9633.779768] [] ? sysfs_hash_and_remove+0x72/0x80
    [ 9633.779786] [] ipmi_pnp_remove+0xd/0xf [ipmi_si]
    [ 9633.779802] [] pnp_device_remove+0x1b/0x40

    Fix this by initializing spinlocks in a smi_info_alloc() helper function,
    right after memory allocation and clearing.

    Signed-off-by: Eric Dumazet
    Acked-by: David Miller
    Cc: Yinghai Lu
    Acked-by: Corey Minyard
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Eric Dumazet
     
  • This is a bug fix. Some SPI connected devices using 16/24 bit accesses,
    previously failed, now work.

    This typo slipped in after testing, during some restructuring.

    Signed-off-by: Michael Hennerich
    Cc: Mike Frysinger
    Cc: Chris Verges
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Michael Hennerich
     
  • The linker script cleanup that I did in commit 5d150a97f93 ("um: Clean up
    linker script using standard macros.") (2.6.32) accidentally introduced an
    ALIGN(PAGE_SIZE) when converting to use INIT_TEXT_SECTION; Richard
    Weinberger reported that this causes the kernel to segfault with
    CONFIG_STATIC_LINK=y.

    I'm not certain why this extra alignment is a problem, but it seems likely
    it is because previously

    __init_begin = _stext = _text = _sinittext

    and with the extra ALIGN(PAGE_SIZE), _sinittext becomes different from the
    rest. So there is likely a bug here where something is assuming that
    _sinittext is the same as one of those other symbols. But reverting the
    accidental change fixes the regression, so it seems worth committing that
    now.

    Signed-off-by: Tim Abbott
    Reported-by: Richard Weinberger
    Cc: Jeff Dike
    Tested by: Antoine Martin
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Richard Weinberger
     
  • …structures have been torn down

    Under some workloads, some channel messages have been observed being
    delayed on the sending side past the point where the receiving side has
    been able to tear down its partition structures.

    This condition is already detected in xpc_handle_activate_IRQ_uv(), but
    that information is not given to xpc_handle_activate_mq_msg_uv(). As a
    result, xpc_handle_activate_mq_msg_uv() assumes the structures still exist
    and references them, causing a NULL-pointer deref.

    Signed-off-by: Robin Holt <holt@sgi.com>
    Cc: <stable@kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    Robin Holt
     
  • This fixes a issue which was introduced by fe2cc53e ("uml: track and make
    up lost ticks").

    timeval_to_ns() returns long long and not int. Due to that UML's timer
    did not work properlt and caused timer freezes.

    Signed-off-by: Richard Weinberger
    Acked-by: Pekka Enberg
    Cc: Jeff Dike
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Richard Weinberger