43f5e655ef
Separate just the changing of mount flags (MS_REMOUNT|MS_BIND) from full
remount because the mount data will get parsed with the new fs_context
stuff prior to doing a remount - and this causes the syscall to fail under
some circumstances.
To quote Eric's explanation:
[...] mount(..., MS_REMOUNT|MS_BIND, ...) now validates the mount options
string, which breaks systemd unit files with ProtectControlGroups=yes
(e.g. systemd-networkd.service) when systemd does the following to
change a cgroup (v1) mount to read-only:
mount(NULL, "/run/systemd/unit-root/sys/fs/cgroup/systemd", NULL,
MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_REMOUNT|MS_BIND, NULL)
... when the kernel has CONFIG_CGROUPS=y but no cgroup subsystems
enabled, since in that case the error "cgroup1: Need name or subsystem
set" is hit when the mount options string is empty.
Probably it doesn't make sense to validate the mount options string at
all in the MS_REMOUNT|MS_BIND case, though maybe you had something else
in mind.
This is also worthwhile doing because we will need to add a mount_setattr()
syscall to take over the remount-bind function.
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.