Ok, the grep -A2 wasn't that bright XD. With -C2 I just got
16:19:23.935175 --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
16:19:23.937296 faccessat(AT_FDCWD, "/smb/server/share/dir/", F_OK) =
-1 EINTR (Interrupted system call)
[...]
16:19:34.191156 --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
16:19:34.192562 stat("/smb/server/share/dir/subdir", 0x7fff40feb5c0) =
-1 EINTR (Interrupted system call)
[...]
16:19:39.358023 --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED,
si_pid=68151, si_uid=501, si_status=0, si_utime=1, si_stime=1} ---
16:19:39.358477 stat("/smb/server/share/dir", 0x7fff40fea8b0) = -1
EINTR (Interrupted system call)
[...]
16:20:01.111670 --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
16:20:01.113070 stat("/smb/server/share/dir/subdir", 0x7fff40feb5c0) =
-1 EINTR (Interrupted system call)
[...]
16:20:05.519682 --- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
16:20:05.520931 stat("/smb/server/share/dir/subdir", 0x7fff40feb5c0) =
-1 EINTR (Interrupted system call)
which makes a bit more sense I guess.
Tobias
---
On 12.02.21 16:11, Tobias Bading wrote:
Hi.
Everyone doing alright hacking/working from home?
Yesterday I encountered a curious problem while using (a self-built)
Emacs 26.3.50 on my GNU/Linux machine at home:
I've set up the automounter to mount SMB shares of Windows servers in
the office through the company's VPN. This works fine for e.g. "ls
-lR /smb/server/share/dir" in a shell, except for bad performance.
The problems start when I try to work with the same directory from
within Emacs with dired-mode, i.e. a simple C-x C-f
/smb/server/share/dir. Quite regularly I get errors like
"dired-get-file-for-visit: File no longer exists; type ‘g’ to update
Dired buffer", although nothing has changed in the directory.
So I put Emacs under a microscope with
strace -f -e trace=%file -tt emacs 2>&1 | grep --line-buffered -A2
/smb/ >emacs.log
which revealed errors like
faccessat(AT_FDCWD, "/smb/server/share/dir", F_OK) = -1 EINTR
(Interrupted system call)
--- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
[...]
stat("/smb/server/share/dir", 0x7fffe49383b0) = -1 EINTR (Interrupted
system call)
--- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
--- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
(The timestamps of the SIGIO lines suggest that these signals have
nothing to do with the EINTR errors reported beforehand, the
timestamps are often over 0.1 seconds apart.)
So far I've only seen stat() and faccessat() failing with EINTR. The
funny thing is, the man pages of those two system calls don't mention
EINTR at all. man signal(7) also doesn't mention these functions in
the paragraph about SA_RESTART. Anyway, I've checked the source code
of my Emacs 26.3.50 build and found emacs_sigaction_flags() in
src/sysdep.c, which does return 0 (as intended by the dev(s) who
wrote the code). I've changed the implementation to "return
SA_RESTART;", but that had no effect.
To make sure I didn't mess up my own Emacs 26 git branch somehow, I
did a quick test with the current HEAD of origin/master and
"src/emacs -Q", which seems to have the same problem, revealed by
error messages like "apply: Setting current directory: Interrupted
system call, /smb/server/share/dir/".
I'm stumped. A (shell-command "ls -lAFNR /smb/server/share/big-dir/")
works fine, as does a "cp -a" of that directory. But when the Emacs
process itself calls stat() or faccessat(), things go sideways? Why?
What am I missing? Are stat() and faccessat() even allowed to fail
with EINTR? Is this a kernel bug, maybe somewhere in the CIFS client
implementation? But an strace of "ls -lAFNR
/smb/server/share/big-dir/" shows not a single EINTR! So why would
only Emacs be affected?
Please enlighten me... ;)
Tobias