lkml.org 
[lkml]   [2010]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [Bisected Regression in 2.6.35] A full tmpfs filesystem causeshibernation to hang
    Date
    > === 8< ===
    > PM: Marking nosave pages: ...0009f000 - ...000100000
    > PM: basic memory bitmaps created
    > PM: Syncing filesystems ... done
    > Freezing user space processes ... (elapsed 0.01 seconds) done.
    > Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
    > PM: Preallocating image memory...
    > shrink_all_memory start
    > PM: shrink memory: pass=1, req:310171 reclaimed:15492 free:360936
    > PM: shrink memory: pass=2, req:294679 reclaimed:28864 free:373981
    > PM: shrink memory: pass=3, req:265815 reclaimed:60311 free:405374
    > PM: shrink memory: pass=4, req:205504 reclaimed:97870 free:443024
    > PM: shrink memory: pass=5, req:107634 reclaimed:146948 free:492141
    > shrink_all_memory: req:107634 reclaimed:146948 free:492141
    > PM: preallocate_image_highmem 556658 278329
    > PM: preallocate_image_memory 103139 103139
    > PM: preallocate_highmem_fraction 183908 556658 760831 -> 183908
    > === >8 ===

    Rafael, this log mean hibernate_preallocate_memory() has a bug.
    It allocate memory as following order.
    1. preallocate_image_highmem() (i.e. __GFP_HIGHMEM)
    2. preallocate_image_memory() (i.e. GFP_KERNEL)
    3. preallocate_highmem_fraction (i.e. __GFP_HIGHMEM)
    4. preallocate_image_memory() (i.e. GFP_KERNEL)

    But, please imazine following scenario (as Vefa's scenario).
    - system has 3GB memory. 1GB is normal. 2GB is highmem.
    - all normal memory is free
    - 1.5GB memory of highmem are used for tmpfs. rest 500MB is free.

    At that time, hibernate_preallocate_memory() works as following.

    1. call preallocate_image_highmem(1GB)
    2. call preallocate_image_memory(500M) total 1.5GB allocated
    3. call preallocate_highmem_fraction(660M) total 2.2GB allocated

    then, all of normal zone memory was exhaust. next preallocate_image_memory()
    makes OOM, and oom_killer_disabled makes infinite loop.
    (oom_killer_disabled careless is vmscan bug. I'll fix it soon)

    The problem is, alloc_pages(__GFP_HIGHMEM) -> alloc_pages(GFP_KERNEL) is
    wrong order. alloc_pages(__GFP_HIGHMEM) may allocate page from lower zone.
    then, next alloc_pages(GFP_KERNEL) lead to OOM.

    Please consider alloc_pages(GFP_KERNEL) -> alloc_pages(__GFP_HIGHMEM) order.
    Even though vmscan fix can avoid infinite loop, OOM situation might makes
    big slow down on highmem machine. It seems no good.


    Thanks.




    \
     
     \ /
      Last update: 2010-09-01 02:51    [W:3.615 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site