On 14/11/2016 14:00, Henri Hennebert wrote: > On 11/14/2016 12:45, Andriy Gapon wrote: >> Okay. Luckily for us, it seems that 'm' is available in frame 5. It also >> happens to be the first field of 'struct faultstate'. So, could you please >> go >> to frame and print '*m' and '*(struct faultstate *)m' ? >> > (kgdb) fr 4 > #4 0xffffffff8089d1c1 in vm_page_busy_sleep (m=0xfffff800df68cd40, > wmesg=<value > optimized out>) at /usr/src/sys/vm/vm_page.c:753 > 753 msleep(m, vm_page_lockptr(m), PVM | PDROP, wmesg, 0); > (kgdb) print *m > $1 = {plinks = {q = {tqe_next = 0xfffff800dc5d85b0, tqe_prev = > 0xfffff800debf3bd0}, s = {ss = {sle_next = 0xfffff800dc5d85b0}, > pv = 0xfffff800debf3bd0}, memguard = {p = 18446735281313646000, v = > 18446735281353604048}}, listq = {tqe_next = 0x0, > tqe_prev = 0xfffff800dc5d85c0}, object = 0xfffff800b62e9c60, pindex = 11, > phys_addr = 3389358080, md = {pv_list = { > tqh_first = 0x0, tqh_last = 0xfffff800df68cd78}, pv_gen = 426, pat_mode > = > 6}, wire_count = 0, busy_lock = 6, hold_count = 0, > flags = 0, aflags = 2 '\002', oflags = 0 '\0', queue = 0 '\0', psind = 0 > '\0', > segind = 3 '\003', order = 13 '\r', > pool = 0 '\0', act_count = 0 '\0', valid = 0 '\0', dirty = 0 '\0'}
If I interpret this correctly the page is in the 'exclusive busy' state. Unfortunately, I can't tell much beyond that. But I am confident that this is the root cause of the lock-up. > (kgdb) print *(struct faultstate *)m > $2 = {m = 0xfffff800dc5d85b0, object = 0xfffff800debf3bd0, pindex = 0, > first_m = > 0xfffff800dc5d85c0, > first_object = 0xfffff800b62e9c60, first_pindex = 11, map = 0xca058000, > entry > = 0x0, lookup_still_valid = -546779784, > vp = 0x6000001aa} > (kgdb) I was wrong on this one as 'm' is actually a pointer, so the above is not correct. Maybe 'info reg' in frame 5 would give a clue about the value of 'fs'. I am not sure how to proceed from here. The only thing I can think of is a lock order reversal between the vnode lock and the page busying quasi-lock. But examining the code I can not spot it. Another possibility is a leak of a busy page, but that's hard to debug. How hard is it to reproduce the problem? Maybe Konstantin would have some ideas or suggestions. -- Andriy Gapon _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"