From 370fed74b4c4a29efd3f888b7c742a4c96dfb6dc Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Fri, 20 Apr 2018 09:50:04 +0200 Subject: [PATCH] umount: add note about --lazy Unfortunately, it's pretty common that users on production systems use lazy umount to fix some FS issues. The usual result is unwanted system reboot, because -l is not the right way how to fix unreachable NFS or mess with local FS with submounts. Note that after lazy umount /proc/self/mountinfo does not contain the FS entry, but kernel still references the FS. It makes it very difficult to debug. Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1566674 Suggested-by: Steve Dickson Signed-off-by: Karel Zak --- sys-utils/umount.8 | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/sys-utils/umount.8 b/sys-utils/umount.8 index 1e27f01f89..fb0601c6d1 100644 --- a/sys-utils/umount.8 +++ b/sys-utils/umount.8 @@ -55,7 +55,8 @@ working directory there, or when a swap file on it is in use. The offending process could even be .B umount itself - it opens libc, and libc in its turn may open for example locale -files. A lazy unmount avoids this problem. +files. A lazy unmount avoids this problem, but it may introduce another +issues. See \fB\-\-lazy\fR description bellow. .SH OPTIONS .TP .BR \-a , " \-\-all" @@ -119,6 +120,13 @@ By default such a helper program is called if it exists. Lazy unmount. Detach the filesystem from the file hierarchy now, and clean up all references to this filesystem as soon as it is not busy anymore. + +A system reboot would be expected in near future if you're going to use this +option for network filesystem or local filesystem with submounts. The +recommended use-case for \fBumount -l\fR is to prevent hangs on shutdown due to +an unreachable network share where a normal umount will hang due to a downed +server or a network partition. Remounts of the share will not be possible. + .TP .BR \-n , " \-\-no\-mtab" Unmount without writing in -- 2.39.2