Hi, On 2023-04-10 19:27:27 +1200, Thomas Munro wrote: > On Mon, Apr 10, 2023 at 2:57 PM Andres Freund <and...@anarazel.de> wrote: > > Have you tried to write a reproducer for this that doesn't involve postgres? > > I tried a bit. I'll try harder soon. > > > ... What kernel version did you repro > > this on Thomas? > > Debian's 6.0.10-2 kernel (Debian 12 on a random laptop). Here's how I > set up a test btrfs in case someone else wants a head start: > > truncate -s2G 2GB.img > sudo losetup --show --find 2GB.img > sudo mkfs -t btrfs /dev/loop0 # the device name shown by losetup > sudo mkdir /mnt/tmp > sudo mount /dev/loop0 /mnt/tmp > sudo chown $(whoami) /mnt/tmp > > cd /mnt/tmp > /path/to/initdb -D pgdata > ... (see instructions further up for postgres command line + queries to run)
I initially failed to repro the issue with these instructions. Turns out that the problem does not happen if huge pages are in used - I'd configured huge pages, so the default huge_pages=try succeeded. As soon as I disable huge_pages explicitly, it reproduces. Another interesting bit is that if checksums are enabled, I also can't reproduce the issue. Together with the huge_page issue, it does suggest that this is somehow related to page faults. Which fits with the thread Andrea referenced... Greetings, Andres Freund
