https://bugzilla.samba.org/show_bug.cgi?id=15123 Bug ID: 15123 Summary: getxattr() on cifs sometimes hangs since kernel 5.14 Product: CifsVFS Version: 5.x Hardware: All OS: All Status: NEW Severity: normal Priority: P5 Component: kernel fs Assignee: sfrench@xxxxxxxxx Reporter: forestix@xxxxxxxxx QA Contact: cifs-qa@xxxxxxxxx Target Milestone: --- Created attachment 17423 --> https://bugzilla.samba.org/attachment.cgi?id=17423&action=edit possible reproducer When running on recent kernel versions, this system call on a cifs-mounted file sometimes takes an unusually long time: getxattr("/cifsmount/dir/image.jpg", "user.baloo.rating", NULL, 0) The call normally returns in under 10 milliseconds, but on kernel 5.14+, it sometimes takes over 30 seconds with no significant client or server load. Discovered while using gwenview to browse 100+ 1.5 MiB images on a samba share mounted via /etc/fstab. While quickly flipping through the images, the problem often occurs within 20 seconds. Gwenview freezes until the call completes. Client: kernel versions 5.14 and later mount.cifs 6.11 Gwenview 20.12.3 Debian Bullseye 4-core amd64 Server: Samba 4.13.13-Debian Debian Bullseye 6-core arm64 A git bisect identified kernel commit 9e992755be8f as the problematic change. The problem does not occur when any of the following are true: - Client is running a kernel from before that commit. - The nouser_xattr mount option is used on the cifs share. - Gwenview accesses the files via smb:// URL instead of a cifs mount. I don't know Gwenview's internals, but using its strace output as a guide, I have written a potential reproducer. It succeeds at triggering slow getxattr() calls, though not nearly as slow as those triggered by Gwenview. I will attach it to this report. Originally reported in May 2022 on the linux-cifs mailing list: https://www.spinics.net/lists/linux-cifs/msg25316.html -- You are receiving this mail because: You are the QA Contact for the bug.
