I left my fuzzing box running for the weekend, and checked in on it this evening, to find that none of the child processes were making any progress. cat'ing /proc/n/stack shows them all stuck in the same place.. Some examples: [<ffffffffbe163444>] lru_add_drain_all+0x34/0x200 [<ffffffffbe1850d3>] SyS_mlock+0x33/0x130 [<ffffffffbe7451b9>] ia32_sysret+0x0/0x5 [<ffffffffffffffff>] 0xffffffffffffffff [<ffffffffbe163444>] lru_add_drain_all+0x34/0x200 [<ffffffffbe1852fd>] SyS_mlockall+0xad/0x1a0 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff [<ffffffffbe163444>] lru_add_drain_all+0x34/0x200 [<ffffffffbe1850d3>] SyS_mlock+0x33/0x130 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff [<ffffffffbe163444>] lru_add_drain_all+0x34/0x200 [<ffffffffbe1b2dae>] SYSC_move_pages+0x2be/0x7c0 [<ffffffffbe1b32be>] SyS_move_pages+0xe/0x10 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff [<ffffffffbe089d41>] flush_work+0x1d1/0x290 [<ffffffffbe16358b>] lru_add_drain_all+0x17b/0x200 [<ffffffffbe1b2dae>] SYSC_move_pages+0x2be/0x7c0 [<ffffffffbe1b32be>] SyS_move_pages+0xe/0x10 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff [<ffffffffbe163444>] lru_add_drain_all+0x34/0x200 [<ffffffffbe1b133e>] migrate_prep+0xe/0x20 [<ffffffffbe1a22a0>] do_migrate_pages+0x40/0x2e0 [<ffffffffbe1a2889>] SYSC_migrate_pages+0x349/0x3d0 [<ffffffffbe1a292e>] SyS_migrate_pages+0xe/0x10 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff <and more repeated variants of above> The problem seems to be that one of the processes has the mutex.. [<ffffffffbe089d41>] flush_work+0x1d1/0x290 [<ffffffffbe16358b>] lru_add_drain_all+0x17b/0x200 [<ffffffffbe1b2dae>] SYSC_move_pages+0x2be/0x7c0 [<ffffffffbe1b32be>] SyS_move_pages+0xe/0x10 [<ffffffffbe74366a>] tracesys+0xd4/0xd9 [<ffffffffffffffff>] 0xffffffffffffffff but that flush_work doesn't seem to ever complete. meminfo looks like this: MemTotal: 7959748 kB MemFree: 7133336 kB MemAvailable: 7112444 kB Buffers: 5720 kB Cached: 160712 kB SwapCached: 43248 kB Active: 328040 kB Inactive: 171252 kB Active(anon): 319172 kB Inactive(anon): 145732 kB Active(file): 8868 kB Inactive(file): 25520 kB Unevictable: 8 kB Mlocked: 20 kB SwapTotal: 8011772 kB SwapFree: 7936572 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 291280 kB Mapped: 52676 kB Shmem: 132044 kB Slab: 206256 kB SReclaimable: 92760 kB SUnreclaim: 113496 kB KernelStack: 1856 kB PageTables: 9244 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 11991644 kB Committed_AS: 2470095756 kB VmallocTotal: 34359738367 kB VmallocUsed: 594580 kB VmallocChunk: 34359067436 kB HardwareCorrupted: 0 kB AnonHugePages: 192512 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 8151108 kB DirectMap2M: 18446744073709541376 kB DirectMap1G: 0 kB That DirectMap2M looks kind of ridiculous, is that it? /proc//maps for the pid that's stuck in the flush looks like this: 00400000-0042f000 r-xp 00000000 08:05 671186187 /home/davej/src/trinity/tmp/trinity.7bIfPZ/trinity 0062e000-0062f000 r--p 0002e000 08:05 671186187 /home/davej/src/trinity/tmp/trinity.7bIfPZ/trinity 0062f000-00690000 rw-p 0002f000 08:05 671186187 /home/davej/src/trinity/tmp/trinity.7bIfPZ/trinity 00690000-00691000 rw-p 00000000 00:00 0 024bf000-026f0000 rw-p 00000000 00:00 0 [heap] 026f0000-02be1000 rw-p 00000000 00:00 0 [heap] 02be1000-02db5000 rwxp 00000000 00:00 0 [heap] 7f686032b000-7f6860d2b000 -w-s 00000000 00:03 14115504 /dev/zero (deleted) 7f6860d2b000-7f686172b000 -w-s 00000000 00:03 14111702 /dev/zero (deleted) 7f686172b000-7f686212b000 -w-s 00000000 00:03 14109886 /dev/zero (deleted) 7f686212b000-7f6862b2b000 -w-s 00000000 00:03 14105135 /dev/zero (deleted) 7f6862b2b000-7f686352b000 -w-s 00000000 00:03 14102702 /dev/zero (deleted) 7f686352b000-7f6863f2b000 -w-s 00000000 00:03 14094076 /dev/zero (deleted) 7f6863f2b000-7f686492b000 r--s 00000000 00:03 14115503 /dev/zero (deleted) 7f686492b000-7f686532b000 rw-s 00000000 00:03 14115502 /dev/zero (deleted) 7f686532b000-7f686572b000 -w-s 00000000 00:03 14115501 /dev/zero (deleted) 7f686572b000-7f6865b2b000 r--s 00000000 00:03 14115500 /dev/zero (deleted) 7f6865b2b000-7f6865f2b000 rw-s 00000000 00:03 14115499 /dev/zero (deleted) 7f6865f2b000-7f686612b000 -w-s 00000000 00:03 14115498 /dev/zero (deleted) 7f686612b000-7f686632b000 r--s 00000000 00:03 14115497 /dev/zero (deleted) 7f686632b000-7f686652b000 rw-s 00000000 00:03 14115496 /dev/zero (deleted) 7f686652b000-7f686662b000 -w-s 00000000 00:03 14115495 /dev/zero (deleted) 7f686662b000-7f686672b000 r--s 00000000 00:03 14115494 /dev/zero (deleted) 7f686672b000-7f686682b000 rw-s 00000000 00:03 14115493 /dev/zero (deleted) 7f686682b000-7f6866836000 r-xp 00000000 08:03 924881 /usr/lib64/libnss_files-2.18.so 7f6866836000-7f6866a35000 ---p 0000b000 08:03 924881 /usr/lib64/libnss_files-2.18.so 7f6866a35000-7f6866a36000 r--p 0000a000 08:03 924881 /usr/lib64/libnss_files-2.18.so 7f6866a36000-7f6866a37000 rw-p 0000b000 08:03 924881 /usr/lib64/libnss_files-2.18.so 7f6866a37000-7f6866beb000 r-xp 00000000 08:03 924770 /usr/lib64/libc-2.18.so 7f6866beb000-7f6866deb000 ---p 001b4000 08:03 924770 /usr/lib64/libc-2.18.so 7f6866deb000-7f6866def000 r--p 001b4000 08:03 924770 /usr/lib64/libc-2.18.so 7f6866def000-7f6866df1000 rw-p 001b8000 08:03 924770 /usr/lib64/libc-2.18.so 7f6866df1000-7f6866df6000 rw-p 00000000 00:00 0 7f6866df6000-7f6866e16000 r-xp 00000000 08:03 924755 /usr/lib64/ld-2.18.so 7f6866ea3000-7f6866f03000 rw-p 00000000 00:00 0 7f6866f03000-7f6866f05000 -w-s 00000000 00:03 14115492 /dev/zero (deleted) 7f6866f05000-7f6866f07000 r--s 00000000 00:03 14115491 /dev/zero (deleted) 7f6866f07000-7f6866f09000 rw-s 00000000 00:03 14115490 /dev/zero (deleted) 7f6866f09000-7f6866f0a000 rw-s 00000000 00:03 14094061 /dev/zero (deleted) 7f6866f0a000-7f6866f0b000 rw-s 00000000 00:03 14094060 /dev/zero (deleted) 7f6866f0b000-7f6866f0c000 rw-s 00000000 00:03 14094059 /dev/zero (deleted) 7f6866f0c000-7f6866f0d000 rw-s 00000000 00:03 14094058 /dev/zero (deleted) 7f6866f0d000-7f6866f0e000 rw-s 00000000 00:03 14094057 /dev/zero (deleted) 7f6866f0e000-7f6866f0f000 rw-s 00000000 00:03 14094056 /dev/zero (deleted) 7f6866f0f000-7f6866f10000 rw-s 00000000 00:03 14094055 /dev/zero (deleted) 7f6866f10000-7f6866f11000 rw-s 00000000 00:03 14094054 /dev/zero (deleted) 7f6866f11000-7f6866f12000 rw-s 00000000 00:03 14094053 /dev/zero (deleted) 7f6866f12000-7f6866f13000 rw-s 00000000 00:03 14094052 /dev/zero (deleted) 7f6866f13000-7f6866f14000 rw-s 00000000 00:03 14094051 /dev/zero (deleted) 7f6866f14000-7f6866f15000 rw-s 00000000 00:03 14094050 /dev/zero (deleted) 7f6866f15000-7f6866f16000 rw-s 00000000 00:03 14094049 /dev/zero (deleted) 7f6866f16000-7f6866f17000 rw-s 00000000 00:03 14094048 /dev/zero (deleted) 7f6866f17000-7f6866f18000 rw-s 00000000 00:03 14094047 /dev/zero (deleted) 7f6866f18000-7f6866f19000 rw-s 00000000 00:03 14094046 /dev/zero (deleted) 7f6866f19000-7f6866f1a000 rw-s 00000000 00:03 14094045 /dev/zero (deleted) 7f6866f1a000-7f6866f1b000 rw-s 00000000 00:03 14094044 /dev/zero (deleted) 7f6866f1b000-7f6866f1c000 rw-s 00000000 00:03 14094043 /dev/zero (deleted) 7f6866f1c000-7f6866f3a000 ---s 00000000 00:03 14094035 /dev/zero (deleted) 7f6866f3a000-7f6866f3f000 rw-s 0001e000 00:03 14094035 /dev/zero (deleted) 7f6866f3f000-7f6866f5d000 ---s 00023000 00:03 14094035 /dev/zero (deleted) 7f6866f5d000-7f6866fb8000 rw-s 00000000 00:03 14094034 /dev/zero (deleted) 7f6866fb8000-7f6867009000 rw-s 00000000 00:03 14094033 /dev/zero (deleted) 7f6867009000-7f686700c000 rw-p 00000000 00:00 0 7f686700c000-7f686700d000 rw-s 00000000 00:03 14094042 /dev/zero (deleted) 7f686700d000-7f686700e000 rw-s 00000000 00:03 14094041 /dev/zero (deleted) 7f686700e000-7f686700f000 rw-s 00000000 00:03 14094040 /dev/zero (deleted) 7f686700f000-7f6867010000 rw-s 00000000 00:03 14094039 /dev/zero (deleted) 7f6867010000-7f6867011000 rw-s 00000000 00:03 14094038 /dev/zero (deleted) 7f6867011000-7f6867012000 rw-s 00000000 00:03 14094037 /dev/zero (deleted) 7f6867012000-7f6867013000 rw-s 00000000 00:03 14094036 /dev/zero (deleted) 7f6867013000-7f6867015000 rw-p 00000000 00:00 0 7f6867015000-7f6867016000 r--p 0001f000 08:03 924755 /usr/lib64/ld-2.18.so 7f6867016000-7f6867017000 rw-p 00020000 08:03 924755 /usr/lib64/ld-2.18.so 7f6867017000-7f6867018000 rw-p 00000000 00:00 0 7fff21aad000-7fff21ace000 rw-p 00000000 00:00 0 [stack] 7fff21b94000-7fff21b95000 r-xp 00000000 00:00 0 [vdso] ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall] any ideas ? Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>