While fuzz testing a UML (guest 3.12-rc6, host 3.11.6, both 32 bit) with trinity, where the UML guest act both as a NFS server and its own NSF client, and furthermore uses hostfs too as a lcoation of the victims fiels for trinity, I realized that at the host side 1 linux process consumes 100% of its CPU core. A gdb back trace shows :
tfoerste@n22 ~ $ sudo gdb /home/tfoerste/devel/linux/linux 12389 -n -batch -ex bt radix_tree_next_chunk (root=0x1, iter=0x49bb7c60, flags=0) at lib/radix-tree.c:770 770 if (node->slots[offset]) #0 radix_tree_next_chunk (root=0x1, iter=0x49bb7c60, flags=0) at lib/radix-tree.c:770 #1 0x080cc11e in find_get_pages (mapping=0x468f6520, start=0, nr_pages=14, pages=0x0) at mm/filemap.c:844 #2 0x080d5c8a in pagevec_lookup (pvec=0x49bb7cc4, mapping=0x1, start=1, nr_pages=1) at mm/swap.c:914 #3 0x080d607a in truncate_inode_pages_range (mapping=0x468f6520, lstart=0, lend=-1) at mm/truncate.c:241 #4 0x080d641f in truncate_inode_pages (mapping=0x1, lstart=1) at mm/truncate.c:358 #5 0x08260818 in hostfs_evict_inode (inode=0x468f6468) at fs/hostfs/hostfs_kern.c:242 #6 0x0811a8af in evict (inode=0x468f6468) at fs/inode.c:549 #7 0x0811b28d in iput_final (inode=<optimized out>) at fs/inode.c:1391 #8 iput (inode=0x468f6468) at fs/inode.c:1409 #9 0x08117628 in dentry_iput (dentry=<optimized out>) at fs/dcache.c:331 #10 d_kill (dentry=0x446fbc60, parent=0x45f77e70) at fs/dcache.c:477 #11 0x08118048 in dentry_kill (dentry=<optimized out>, unlock_on_failure=<optimized out>) at fs/dcache.c:586 #12 dput (dentry=0x446fbc60) at fs/dcache.c:641 #13 0x081048e3 in __fput (file=0x469869c0) at fs/file_table.c:264 #14 0x0810494b in ____fput (work=0x469869c0) at fs/file_table.c:282 #15 0x08094496 in task_work_run () at kernel/task_work.c:123 #16 0x0807efd2 in exit_task_work (task=<optimized out>) at include/linux/task_work.h:21 #17 do_exit (code=1184809984) at kernel/exit.c:787 #18 0x0807f5dd in do_group_exit (exit_code=0) at kernel/exit.c:920 #19 0x0807f649 in SYSC_exit_group (error_code=<optimized out>) at kernel/exit.c:931 #20 SyS_exit_group (error_code=0) at kernel/exit.c:929 #21 0x08062984 in handle_syscall (r=0x48694dd4) at arch/um/kernel/skas/syscall.c:35 #22 0x08074fb5 in handle_trap (local_using_sysemu=<optimized out>, regs=<optimized out>, pid=<optimized out>) at arch/um/os-Linux/skas/process.c:198 #23 userspace (regs=0x48694dd4) at arch/um/os-Linux/skas/process.c:431 #24 0x0805f750 in fork_handler () at arch/um/kernel/process.c:160 #25 0x00000000 in ?? () B/c of fs/hostfs I assume this might be an UML specific thing, but I'm unsure how to narrow doesn this now... -- MfG/Sincerely Toralf Förster pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3 ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135031&iu=/4140/ostg.clktrk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
