This series attempts to fix a reported exception with mmap
on newer kernels.
original regression report follows:
TL;DR: mmap() seems to be broken on 9pfs on Linux 6.4. setting
"rootflags=ignoreqv" fixes it as well, but it feels like a regression.
I'm tracking down an issue which recently turned up in DistroKit [1] (an
embedded Linux distro based on the ptxdist build system). The issue was a bit
uggly, as my CI didn't find it (systems boot up normally after a while, and I
only use 9p for virtual qemu machines, while most of the test farm is real
hardware).
The qemu machine in question is qemu-system-arm, emulating an ARM v7a machine.
When starting the systems interactively, I get a lot of error output from
ldconfig, like this:
[ 17.412964] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libgcc_s.so.1.
[ 17.418851] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libstdc++.so.
[ 17.425009] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libstdc++.so.6.0.30.
[ 17.436671] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libstdc++.so.6.
[ 17.448451] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libatomic.so.
[ 17.456418] systemd-rc-once[127]: ldconfig: Cannot mmap file /lib/libatomic.so.1.2.0.
...
Running ldconfig with strace shows this, for all libraries::
| statx(AT_FDCWD, "/lib/libnm.so.0", AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW|AT_NO_AUTOMOUNT, STATX_BASIC_STATS, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFLNK|0777, stx_size=14, ...}) = 0
| statx(AT_FDCWD, "/lib/libnm.so.0", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_BASIC_STATS, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|064 4, stx_size=862228, ...}) = 0
| openat(AT_FDCWD, "/lib/libnm.so.0", O_RDONLY|O_LARGEFILE) = 4
| statx(4, "", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT|AT_EMPTY_PATH, STATX_BASIC_STATS, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0644, stx_s ize=862228, ...}) = 0
| mmap2(NULL, 862228, PROT_READ, MAP_SHARED, 4, 0) = -1 ENODEV (No such device)
| write(2, "ldconfig: ", 10ldconfig: ) = 10
| write(2, "Cannot mmap file /lib/libnm.so.0"..., 34Cannot mmap file /lib/libnm.so.0.) = 34
| write(2, "\n", 1) = 1
| close(4) = 0
I could track down the breakage to
1543b4c5071c54d76aad7a7a26a6e43082269b0c
My test setup has, in addition to the patch above, the following patches also
reverted on top of a vanilla 6.4 kernel:
4eb3117888a923f6b9b1ad2dd093641c49a63ae5
21e26d5e54ab7cfe6b488fd27d4d70956d07e03b
as 1543b cannot be reverted without those; however, the effect only goes away
when I also revert 1543b. The kernel has no other patches applied, only these
three reverts.
Reported-by: Robert Schwebel <[email protected]>
Signed-off-by: Eric Van Hensbergen <[email protected]>
---
Changes in v2:
- fix requested changes in commit messages
- add patch to remove unnecessary invalidate_inode_pages in mmap readonly path
- Link to v1: https://lore.kernel.org/r/20230716-fixes-overly-restrictive-mmap-v1-0-0683b283b932@kernel.org
---
Eric Van Hensbergen (4):
fs/9p: remove unnecessary and overrestrictive check
fs/9p: fix typo in comparison logic for cache mode
fs/9p: fix type mismatch in file cache mode helper
fs/9p: remove unnecessary invalidate_inode_pages2
fs/9p/fid.h | 6 +++---
fs/9p/vfs_file.c | 3 ---
2 files changed, 3 insertions(+), 6 deletions(-)
---
base-commit: 95f41d87810083d8b3dedcce46a4e356cf4a9673
change-id: 20230716-fixes-overly-restrictive-mmap-30a23501e787
Best regards,
--
Eric Van Hensbergen <[email protected]>
There were two flags (s_flags and s_cache) which had incorrect signed
type in the parameters of the file cache mode helper function.
Reviewed-by: Dominique Martinet <[email protected]>
Signed-off-by: Eric Van Hensbergen <[email protected]>
---
fs/9p/fid.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/9p/fid.h b/fs/9p/fid.h
index 297c2c377e3dd..29281b7c38870 100644
--- a/fs/9p/fid.h
+++ b/fs/9p/fid.h
@@ -46,8 +46,8 @@ static inline struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
* NOTE: these are set after open so only reflect 9p client not
* underlying file system on server.
*/
-static inline void v9fs_fid_add_modes(struct p9_fid *fid, int s_flags,
- int s_cache, unsigned int f_flags)
+static inline void v9fs_fid_add_modes(struct p9_fid *fid, unsigned int s_flags,
+ unsigned int s_cache, unsigned int f_flags)
{
if (fid->qid.type != P9_QTFILE)
return;
--
2.39.2