[uml-devel] where is pid 16666

[uml-devel] where is pid 16666

[Toralf Förster]

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Fuzzying a 32 bit Linux guest (linux v3.14-rc3-168-g960dfc4) with trinity (1.1-1082-gda55d79) yields again into the situation, that the fuzz job does not continue after a trinity run was finished and the next trinity job was prepared to start. There seems to be an endless loop thru the radix-tree code.

The UML guest itself is responding and works well, login with ssh into it works fine.
After running into this with ext4 file systems in former times now I run into this while using a BTRFS file system for the victim files.
What let me wonder is, why I cannot see a PID 16666 within the UML guest :
(pls look for         pid = 16666                                                  <----------------------------------)


At the host I run this command to track the host proces which is respinsible that the UML trinity job does not continue:

$> sudo gdb /home/tfoerste/devel/linux/linux 13369 -n -batch -ex 'bt full'

warning: Could not load shared library symbols for linux-gate.so.1.
Do you need "set solib-search-path" or "set sysroot"?
0x08349f4c in radix_tree_next_chunk (root=0x11, iter=0x3f25fca0, flags=18) at lib/radix-tree.c:770
770                                             if (node->slots[offset])
#0  0x08349f4c in radix_tree_next_chunk (root=0x11, iter=0x3f25fca0, flags=18) at lib/radix-tree.c:770
        tag = 0
        rnode = 0x3eb3b6d8
        node = 0x3ed37020
#1  0x080cd51e in find_get_pages (mapping=0x3eb4c8a8, start=0, nr_pages=14, pages=0x12) at mm/filemap.c:844
        iter = {index = 0, next_index = 0, tags = 1059454120}
        slot = 0x11
        ret = 0
#2  0x080d760a in pagevec_lookup (pvec=0x3f25fd04, mapping=0x11, start=17, nr_pages=17) at mm/swap.c:969
No locals.
#3  0x080d7a0a in truncate_inode_pages_range (mapping=0x3eb4c8a8, lstart=0, lend=-1) at mm/truncate.c:241
        start = 0
        end = 4294967295
        partial_end = 0
        pvec = <incomplete type>
#4  0x080d7daf in truncate_inode_pages (mapping=0x11, lstart=77309411345) at mm/truncate.c:358
No locals.
#5  0x082a0f41 in evict_inode_truncate_pages (inode=<optimized out>) at fs/btrfs/inode.c:4596
No locals.
#6  btrfs_evict_inode (inode=0x3eb4c7f0) at fs/btrfs/inode.c:4645
        trans = 0x3eb4c708
        root = 0x4713d920
        rsv = 0x3eb4c714
        global_rsv = 0x1000
        __func__ = "btrfs_evict_inode"
#7  0x0811c3ef in evict (inode=0x3eb4c7f0) at fs/inode.c:549
        op = 0x850c620 <btrfs_super_ops>
        __func__ = "evict"
#8  0x0811cedd in iput_final (inode=<optimized out>) at fs/inode.c:1419
        sb = 0x47111c70
        op = 0x850c620 <btrfs_super_ops>
        drop = 17
#9  iput (inode=0x3eb4c7f0) at fs/inode.c:1437
        __func__ = "iput"
#10 0x08112e36 in do_unlinkat (dfd=5, pathname=0x8061d9c <handle_page_fault+524> "l\376\377\377\213C \213U\340\213\004\020%") at fs/namei.c:3729
        error = 0
        name = 0x3eb4c7f0
        dentry = 0x12
        nd = {path = <incomplete type>, last = {{{hash = 2282126, len = 3}, hash_len = 12887184014}, name = 0x480ed150 "f01"}, root = <incomplete type>, inode = 0x3eb4da70, flags = 0, seq = 4, m_seq = 140, last_type = 0, depth = 0, saved_names = {0x48059e00 "\001", 0x48066d80 "", 0x48059e38 "", 0x8b1e828 "", 0x3f25fe98 "H\273\201\277(\350\261\b\254\376%?\245/\021\bH6\v?\354\376%?\264*\006\b\005", 0x811edd2 <__close_fd+82> "\353\f\215t&", 0x48066d80 "", 0x48059e00 "\001", 0x3f0b3648 "\005"}}
        inode = 0x3eb4c7f0
        delegated_inode = 0x0
        lookup_flags = 0
#11 0x08112fa5 in SYSC_unlinkat (flag=<optimized out>, pathname=<optimized out>, dfd=<optimized out>) at fs/namei.c:3765
No locals.
#12 SyS_unlinkat (dfd=5, pathname=134618524, flag=0) at fs/namei.c:3757
        ret = 17
#13 0x08062ab4 in handle_syscall (r=0x3f0b3648) at arch/um/kernel/skas/syscall.c:35
        syscall = 0
#14 0x08074905 in handle_trap (local_using_sysemu=<optimized out>, regs=<optimized out>, pid=<optimized out>) at arch/um/os-Linux/skas/process.c:198
        status = 1030413288
#15 userspace (regs=0x3f0b3648) at arch/um/os-Linux/skas/process.c:431
        sig = 18
        timer = {it_interval = {tv_sec = 0, tv_usec = 0}, it_value = {tv_sec = 0, tv_usec = 10000}}
        err = 17
        status = 34175
        op = 145877032
        pid = 16666                                                  <----------------------------------
        local_using_sysemu = 2
        si = <incomplete type>
#16 0x0805f770 in fork_handler () at arch/um/kernel/process.c:149
No locals.
#17 0x00000002 in ?? ()
No symbol table info available.

- -- 
MfG/Sincerely
Toralf Förster
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