On Mon, 25 April 2011 Mike Frysinger wrote: > On Sun, Apr 24, 2011 at 22:42, KOSAKI Motohiro wrote: > >> On Sun, 24 April 2011 Bruno PrÃmont wrote: > >> > On an older system I've been running Gentoo's revdep-rebuild to check > >> > for system linking/*.la consistency and after doing most of the work the > >> > system starved more or less, just complaining about stuck tasks now and > >> > then. > >> > Memory usage graph as seen from userspace showed sudden quick increase of > >> > memory usage though only a very few MB were swapped out (c.f. attached RRD > >> > graph). > >> > >> Seems I've hit it once again (though detected before system was fully > >> stalled by trying to reclaim memory without success). > >> > >> This time it was during simple compiling... > >> Gathered info below: > >> > >> /proc/meminfo: > >> MemTotal: Â Â Â Â 480660 kB > >> MemFree: Â Â Â Â Â 64948 kB > >> Buffers: Â Â Â Â Â 10304 kB > >> Cached: Â Â Â Â Â Â 6924 kB > >> SwapCached: Â Â Â Â 4220 kB > >> Active: Â Â Â Â Â Â11100 kB > >> Inactive: Â Â Â Â Â15732 kB > >> Active(anon): Â Â Â 4732 kB > >> Inactive(anon): Â Â 4876 kB > >> Active(file): Â Â Â 6368 kB > >> Inactive(file): Â Â10856 kB > >> Unevictable: Â Â Â Â Â32 kB > >> Mlocked: Â Â Â Â Â Â Â32 kB > >> SwapTotal: Â Â Â Â524284 kB > >> SwapFree: Â Â Â Â 456432 kB > >> Dirty: Â Â Â Â Â Â Â Â80 kB > >> Writeback: Â Â Â Â Â Â 0 kB > >> AnonPages: Â Â Â Â Â6268 kB > >> Mapped: Â Â Â Â Â Â 2604 kB > >> Shmem: Â Â Â Â Â Â Â Â 4 kB > >> Slab: Â Â Â Â Â Â 250632 kB > >> SReclaimable: Â Â Â51144 kB > >> SUnreclaim: Â Â Â 199488 kB Â <--- look big as well... > >> KernelStack: Â Â Â131032 kB Â <--- what??? > > > > KernelStack is used 8K bytes per thread. then, your system should have > > 16000 threads. but your ps only showed about 80 processes. > > Hmm... stack leak? > > i might have a similar report for 2.6.39-rc4 (seems to be working fine > in 2.6.38.4), but for embedded Blackfin systems running gdbserver > processes over and over (so lots of short lived forks) > > i wonder if you have a lot of zombies or otherwise unclaimed resources > ? does `ps aux` show anything unusual ? I've not seen anything special (no big amount of threads behind my about 80 processes, even after kernel oom-killed nearly all processes the hogged memory has not been freed. And no, there are no zombies around). Here it seems to happened when I run 2 intensive tasks in parallel, e.g. (re)emerging gimp and running revdep-rebuild -pi in another terminal. This produces a fork rate of about 100-300 per second. Suddenly kmalloc-128 slabs stop being freed and things degrade. Trying to trace some of the kmalloc-128 slab allocations I end up seeing lots of allocations like this: [ 1338.554429] TRACE kmalloc-128 alloc 0xc294ff00 inuse=30 fp=0xc294ff00 [ 1338.554434] Pid: 1573, comm: collectd Tainted: G W 2.6.39-rc4-jupiter-00187-g686c4cb #1 [ 1338.554437] Call Trace: [ 1338.554442] [<c10aef47>] trace+0x57/0xa0 [ 1338.554447] [<c10b07b3>] alloc_debug_processing+0xf3/0x140 [ 1338.554452] [<c10b0972>] T.999+0x172/0x1a0 [ 1338.554455] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.554459] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.554464] [<c10b0a52>] kmem_cache_alloc+0xb2/0x100 [ 1338.554468] [<c10c08b5>] ? path_put+0x15/0x20 [ 1338.554472] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.554476] [<c10b95d8>] get_empty_filp+0x58/0xc0 [ 1338.554481] [<c10c323f>] path_openat+0x1f/0x320 [ 1338.554485] [<c10a0a4e>] ? __access_remote_vm+0x19e/0x1d0 [ 1338.554490] [<c10c3620>] do_filp_open+0x30/0x80 [ 1338.554495] [<c10b0a30>] ? kmem_cache_alloc+0x90/0x100 [ 1338.554500] [<c10c16f8>] ? getname_flags+0x28/0xe0 [ 1338.554505] [<c10cd522>] ? alloc_fd+0x62/0xe0 [ 1338.554509] [<c10c1731>] ? getname_flags+0x61/0xe0 [ 1338.554514] [<c10b781d>] do_sys_open+0xed/0x1e0 [ 1338.554519] [<c10b7979>] sys_open+0x29/0x40 [ 1338.554524] [<c1391390>] sysenter_do_call+0x12/0x26 [ 1338.556764] TRACE kmalloc-128 alloc 0xc294ff80 inuse=31 fp=0xc294ff80 [ 1338.556774] Pid: 1332, comm: bash Tainted: G W 2.6.39-rc4-jupiter-00187-g686c4cb #1 [ 1338.556779] Call Trace: [ 1338.556794] [<c10aef47>] trace+0x57/0xa0 [ 1338.556802] [<c10b07b3>] alloc_debug_processing+0xf3/0x140 [ 1338.556807] [<c10b0972>] T.999+0x172/0x1a0 [ 1338.556812] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.556817] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.556821] [<c10b0a52>] kmem_cache_alloc+0xb2/0x100 [ 1338.556826] [<c10b95d8>] ? get_empty_filp+0x58/0xc0 [ 1338.556830] [<c10b95d8>] get_empty_filp+0x58/0xc0 [ 1338.556841] [<c121fca8>] ? tty_ldisc_deref+0x8/0x10 [ 1338.556849] [<c10c323f>] path_openat+0x1f/0x320 [ 1338.556857] [<c11e2b3e>] ? fbcon_cursor+0xfe/0x180 [ 1338.556863] [<c10c3620>] do_filp_open+0x30/0x80 [ 1338.556868] [<c10b0a30>] ? kmem_cache_alloc+0x90/0x100 [ 1338.556873] [<c10c5e8e>] ? do_vfs_ioctl+0x7e/0x580 [ 1338.556878] [<c10c16f8>] ? getname_flags+0x28/0xe0 [ 1338.556886] [<c10cd522>] ? alloc_fd+0x62/0xe0 [ 1338.556891] [<c10c1731>] ? getname_flags+0x61/0xe0 [ 1338.556898] [<c10b781d>] do_sys_open+0xed/0x1e0 [ 1338.556903] [<c10b7979>] sys_open+0x29/0x40 [ 1338.556913] [<c1391390>] sysenter_do_call+0x12/0x26 Collectd is system monitoring daemon that counts processes, memory usage an much more, reading lots of files under /proc every 10 seconds. Maybe it opens a process related file at a racy moment and thus prevents the 128 slabs and kernel stacks from being released? Replaying the scenario I'm at: Slab: 43112 kB SReclaimable: 25396 kB SUnreclaim: 17716 kB KernelStack: 16432 kB PageTables: 1320 kB with kmalloc-256 55 64 256 16 1 : tunables 0 0 0 : slabdata 4 4 0 kmalloc-128 66656 66656 128 32 1 : tunables 0 0 0 : slabdata 2083 2083 0 kmalloc-64 3902 3904 64 64 1 : tunables 0 0 0 : slabdata 61 61 0 (and compiling process tree now SIGSTOPped in order to have system not starve immediately so I can look around for information) If I resume one of the compiling process trees both KernelStack and slab (kmalloc-128) usage increase quite quickly (and seems to never get down anymore) - probably at same rate as processes get born (no matter when they end). Bruno > -mike -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
