On Sat, Mar 02, 2013 at 06:42:43PM +0000, Al Viro wrote: > ... what makes you think that it's fown->lock, in the first place? > > > [172635.399651] <<EOE>> [<ffffffff816c3e13>] _raw_read_lock+0x13/0x20 > > [172635.399654] [<ffffffff811a4532>] send_sigio+0x52/0xf0 > > send_sigio() is > [initialization of a local variable to 1] > read_lock(&fown->lock); > [getting type and pid, checking them] > read_lock(&tasklist_lock); > [loop doing the majority of work] > read_unlock(&tasklist_lock); > read_unlock(&fown->lock); > and you are at about 1/3 into the function. Who said it's fown->lock and > not tasklist_lock? Could you check (or post) disassembly of send_sigio > to see which one it is?
FWIW, after having grabbed Ubuntu binary of 3.8.0-8 generic (yours is -7, it's not immediately visible on their site and the odds the damn thing has changed in send_sigio() between those revisions are low): send_sigio: (address is off by 16 compared to yours) ffffffff811a4bf0: e8 cb b5 52 00 callq 0xffffffff816d01c0 (that's __fentry__) ffffffff811a4bf5: 55 push %rbp ffffffff811a4bf6: 48 89 e5 mov %rsp,%rbp ffffffff811a4bf9: 41 57 push %r15 ffffffff811a4bfb: 41 89 d7 mov %edx,%r15d ffffffff811a4bfe: 41 56 push %r14 ffffffff811a4c00: 41 89 f6 mov %esi,%r14d ffffffff811a4c03: 41 55 push %r13 ffffffff811a4c05: 41 54 push %r12 ffffffff811a4c07: 53 push %rbx ffffffff811a4c08: 48 89 fb mov %rdi,%rbx ffffffff811a4c0b: 48 83 ec 10 sub $0x10,%rsp ffffffff811a4c0f: e8 1c 32 52 00 callq 0xffffffff816c7e30 (first _raw_read_lock()) ffffffff811a4c14: 44 8b 4b 10 mov 0x10(%rbx),%r9d ffffffff811a4c18: 41 83 f9 03 cmp $0x3,%r9d ffffffff811a4c1c: 0f 84 a6 00 00 00 je 0xffffffff811a4cc8 ffffffff811a4c22: c7 45 d4 01 00 00 00 movl $0x1,-0x2c(%rbp) ffffffff811a4c29: 4c 8b 63 08 mov 0x8(%rbx),%r12 ffffffff811a4c2d: 4d 85 e4 test %r12,%r12 ffffffff811a4c30: 74 5b je 0xffffffff811a4c8d ffffffff811a4c32: 48 c7 c7 40 60 c0 81 mov $0xffffffff81c06040,%rdi ffffffff811a4c39: 44 89 4d c8 mov %r9d,-0x38(%rbp) ffffffff811a4c3d: e8 ee 31 52 00 callq 0xffffffff816c7e30 ffffffff811a4c42: ... and this was the second one, i.e. read_lock(&tasklist_lock). Note that return address is send_sigio + 0x52, just as in your trace. In other words, tasklist_lock it is... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
