On 8/30/23 17:52, Alex Xu (Hello71) wrote: > Hi all, > > Recently "memfd: improve userspace warnings for missing exec-related > flags" was merged. On my system, this is a regression, not an > improvement, because the entire 256k kernel log buffer (default on x86) > is filled with these warnings and "__do_sys_memfd_create: 122 callbacks > suppressed". I haven't investigated too closely, but the most likely > cause is Wayland libraries. > > This is too serious of a consequence for using an old API, especially > considering how recently the flags were added. The vast majority of > software has not had time to add the flags: glibc does not define the > macros until 2.38 which was released less than one month ago, man-pages > does not document the flags, and according to Debian Code Search, only > systemd, stress-ng, and strace actually pass either of these flags. > > Furthermore, since old kernels reject unknown flags, it's not just a > matter of defining and passing the flag; every program needs to > add logic to handle EINVAL and try again. > > Some other way needs to be found to encourage userspace to add the > flags; otherwise, this message will be patched out because the kernel > log becomes unusable after running unupdated programs, which will still > exist even after upstreams are fixed. In particular, AppImages, > flatpaks, snaps, and similar app bundles contain vendored Wayland > libraries which can be difficult or impossible to update. It's being reverted: https://lore.kernel.org/all/20230902230530.6B663C433C8@xxxxxxxxxxxxxxx/ Meanwhile stable should avoid backporting 434ed3350f57 ("memfd: improve userspace warnings for missing exec-related flags") > Thanks, > Alex.
