Hi Steinar, Thanks for the fast response.
On Sun, 7 Jan 2024 at 20:48, Steinar H. Gunderson <se...@debian.org> wrote: > On Sun, Jan 07, 2024 at 08:21:35PM +0200, Manolis Stamatogiannakis wrote: > > I am trying to get plocate to run on an old ARM-based NAS running Debian > > bookworm. Building the database with updatedb works fine, but plocate > > command itself blocks forever without giving any results back. > > > > I attached gdb to the process, and the source of the problem appears to > > be related to the use of io_uring. > > > > Trying to understand what is going on, I ran plocate under strace as > > root. Surprisingly, it ran without blocking. > > This is interesting, but fundamentally pretty impossible to debug from my > side. It sounds very much like a timing-related bug, which is probably why > strace affects it (everything goes much slower); another common case is > that > one attaches strace to a running process, which causes the io_uring syscall > to return EINTR, which gets things running again. > > Is this reproducible every time? > Yes, it is reproducible every time. I understand this may be very hard to reproduce/debug on your side without access to similar hardware. One could probably try reproducing the behaviour with cpulimit + QEMU, but it's not a guaranteed hit, and I don't really expect anyone to spend their time on that. For now, I'm quite content with having a workaround, and I opened the bug mostly to have the issue and the workaround documented for anyone else that may be affected. If more people turn out to have the same issue on armel, we'll probably also have more input for a source-based fix. So, feel free to mark this as unreproducible for now. Since you are also the author of plocate, it may make sense to expose the -DWITHOUT_URING flag through meson to make compiling without io_uring a bit more straightforward. (Trival patch attached.) > > > * reports an error for not being able to access the database when run > > under strace as user (which sounds like the expected behaviour) > > Yes, this is expected. > > > Architecture: armel (armv5tel) > > Kernel: Linux 6.1.0-17-marvell (UP) > > Is this even supported by Debian anymore? > > It's definitely a niche platform, but it appears to be supported: https://www.debian.org/releases/stable/i386/ch02s01.en.html > /* Steinar */ > -- > Homepage: https://www.sesse.net/ Best regards, Manolis
