issue: assertion w->retval++ < (w->poll_fds->length / sizeof(struct pollfd)) failed at ../unix/poll.c:939 (IP 0xf..) in poll_notify(); halt about nanos

[francescolavra]

Basically this check ensures that the return value of a poll() or ppoll() syscall does not exceed the number of file descriptors nfds supplied in the syscall arguments. Looking at the kernel source code I can't see how this assertion could fail, so no clue at the moment on how to try to reproduce the failure.

[rinor]

Closing this for now, since I'm unable to reproduce it. Will still keep an eye on it and reopen in case of new occurrences.

[rinor]

a different frame trace, same assertion

frame trace: 
ffffc0003987fe10:   ffffffff800c277b	(wait_notify + 00000000000001cb/00000000000003c8)
ffffc0003987fe50:   ffffffff800bf83f	(notify_dispatch_with_arg + 000000000000009f/00000000000001a5)
ffffc0003987fec0:   ffffffff800a922d	(efd_write_bh + 00000000000001cd/00000000000001f2)
ffffc0003987ff20:   ffffffff800a3113	(blockq_check_timeout + 0000000000000063/0000000000000289)
ffffc0003987ff80:   ffffffff800d8d76	(write + 0000000000000166/0000000000000247)
ffffc0003987ffb0:   ffffffff800e1a23	(syscall_handler + 00000000000002f3/0000000000000636)

loaded klibs: 
assertion w->retval++ < (w->poll_fds->length / sizeof(struct pollfd)) failed at /nanos/src/unix/poll.c:939 (IP 0xffffffff800c0c63)  in poll_notify(); halt

[rinor]

It looks like those assertions (and some more), happen when there is not enough free memory for the executing actions.