| Summary: | writev() fails repeatedly with EAGAIN after sendfile() fails with EAGAIN | ||
|---|---|---|---|
| Product: | Base System | Reporter: | YOUZHONG YANG <youzhong> |
| Component: | kern | Assignee: | freebsd-bugs (Nobody) <bugs> |
| Status: | New --- | ||
| Severity: | Affects Only Me | CC: | chris |
| Priority: | --- | ||
| Version: | 11.1-RELEASE | ||
| Hardware: | Any | ||
| OS: | Any | ||
Recently I started evaluating FreeBSD, including the Samba software. Unfortunately once I set 'use sendfile = yes' in Samba, and then tried to launch an application from the samba share, it hung. The application is not a small one, it loads thousands of files from the server to Windows client. It appears the sendfile() failed with EAGAIN: # dtrace -n 'syscall::sendfile:return /arg1 == -1/ {ustack(); printf("errno = %d", errno);}' dtrace: description 'syscall::sendfile:return ' matched 1 probe CPU ID FUNCTION:NAME 23 64274 sendfile:return libc.so.7`__sys_sendfile+0xa libsmbd-base-samba4.so`vfswrap_sendfile+0x127 libsmbd-base-samba4.so`smb_vfs_call_sendfile+0x6d libsmbd-base-samba4.so`smb2_sendfile_send_data+0x8e libtalloc.so.2.1.9`_tc_free_internal+0x152 libtalloc.so.2.1.9`_tc_free_children_internal+0xac libtalloc.so.2.1.9`_tc_free_internal+0x331 libtalloc.so.2.1.9`_talloc_free_internal+0xb2 libtalloc.so.2.1.9`_talloc_free+0x114 libsmbd-base-samba4.so`smbd_smb2_flush_send_queue+0x37a libsmbd-base-samba4.so`smbd_smb2_request_reply+0x1886 libsmbd-base-samba4.so`smbd_smb2_request_done_ex+0x62b libsmbd-base-samba4.so`smbd_smb2_request_read_done+0x32f libtevent.so.0.9.31`_tevent_req_notify_callback+0x6c libsmbd-base-samba4.so`smbd_smb2_request_pending_queue+0x3f libsmbd-base-samba4.so`smbd_smb2_request_process_read+0x4ef libsmbd-base-samba4.so`smbd_smb2_request_dispatch+0x1f03 libsmbd-base-samba4.so`smbd_smb2_io_handler+0x8e2 libsmbd-base-samba4.so`smbd_smb2_connection_handler+0x46 libtevent.so.0.9.31`poll_event_loop_poll+0x75c errno = 35 then Samba process 'smbd' tried to send data using writev(), but writev() failed repeatedly with EAGAIN: # dtrace -n 'syscall::writev:return /arg1 == -1/ {ustack(); printf("errno = %d", errno);}' 16 63748 writev:return libc.so.7`_writev+0xa libsys-rw-samba4.so`sys_writev+0x21 libsys-rw-samba4.so`write_data_iov+0x88 libsys-rw-samba4.so`write_data+0x39 libsmbd-base-samba4.so`fake_sendfile+0x16e libsmbd-base-samba4.so`smb2_sendfile_send_data+0x61a libtalloc.so.2.1.9`_tc_free_internal+0x152 libtalloc.so.2.1.9`_tc_free_children_internal+0xac libtalloc.so.2.1.9`_tc_free_internal+0x331 libtalloc.so.2.1.9`_talloc_free_internal+0xb2 libtalloc.so.2.1.9`_talloc_free+0x114 libsmbd-base-samba4.so`smbd_smb2_flush_send_queue+0x37a libsmbd-base-samba4.so`smbd_smb2_request_reply+0x1886 libsmbd-base-samba4.so`smbd_smb2_request_done_ex+0x62b libsmbd-base-samba4.so`smbd_smb2_request_read_done+0x32f libtevent.so.0.9.31`_tevent_req_notify_callback+0x6c libsmbd-base-samba4.so`smbd_smb2_request_pending_queue+0x3f libsmbd-base-samba4.so`smbd_smb2_request_process_read+0x4ef libsmbd-base-samba4.so`smbd_smb2_request_dispatch+0x1f03 libsmbd-base-samba4.so`smbd_smb2_io_handler+0x8e2 errno = 35 # dtrace -n 'syscall::sendfile:return { @["sendfile", execname, errno] = count();}' -n 'syscall::writev:return { @["writev", execname, errno] = count();}' writev syslogd 0 1 sendfile smbd 35 3 writev unbound 0 5 writev winbindd 0 33 writev smbd 0 1725 sendfile smbd 0 5388 writev smbd 35 276979542 The FreeBSD version is 11.1-RELEASE, and Samba is 4.6.8. I don't know how to reproduce it without using Samba. I can do dtrace. Please let me know what can be done next to find out the root cause of the issue. By the way, I am not familiar with the FreeBSD src code.