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Linus Walleij 49db08c358 chrdev: emit a warning when we go below dynamic major range
Currently a dynamically allocated character device major is taken
from 254 and downward. This mechanism is used for RTC, IIO and a
few other subsystems.

The kernel currently has no check prevening these dynamic
allocations from eating into the assigned numbers at 233 and
downward.

In a recent test it was reported that so many dynamic device
majors were used on a test server, that the major number for
infiniband (231) was stolen. This occurred when allocating a new
major number for GPIO chips. The error messages from the kernel
were not helpful. (See: https://lkml.org/lkml/2016/2/14/124)

This patch adds a defined lower limit of the dynamic major
allocation region will henceforth emit a warning if we start to
eat into the assigned numbers. It does not do any semantic
changes and will not change the kernels behaviour: numbers will
still continue to be stolen, but we will know from dmesg what
is going on.

This also updates the Documentation/devices.txt to clearly
reflect that we are using this range of major numbers for dynamic
allocation.

Reported-by: Ying Huang <ying.huang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-29 10:11:44 -07:00
..
9p wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
adfs fs/adfs/adfs.h: tidy up comments 2016-01-20 17:09:18 -08:00
affs affs_do_readpage_ofs(): just use kmap_atomic() around memcpy() 2016-02-20 00:15:51 -05:00
afs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
autofs4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-03-19 18:52:29 -07:00
befs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
bfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
btrfs Merge branch 'for-linus-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-03-21 18:12:42 -07:00
cachefiles CacheFiles: Provide read-and-reset release counters for cachefilesd 2016-02-01 12:30:10 -05:00
ceph ceph: use kmem_cache_zalloc 2016-03-25 18:51:56 +01:00
cifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-03-19 18:52:29 -07:00
coda Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-01-23 12:24:56 -08:00
configfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-03-19 18:52:29 -07:00
cramfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
crypto f2fs/crypto: fix xts_tweak initialization 2016-03-26 10:13:05 -07:00
debugfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
devpts pty: make sure super_block is still valid in final /dev/tty close 2016-02-06 23:45:46 -08:00
dlm dlm for 4.6 2016-03-17 16:38:36 -07:00
ecryptfs Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-03-23 06:12:39 -07:00
efivarfs efi: Make efivarfs entries immutable by default 2016-02-10 16:25:52 +00:00
efs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
exofs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
exportfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ext2 Performance improvements in SEEK_DATA and xattr scalability 2016-03-17 16:31:18 -07:00
ext4 ext4: in ext4_dir_llseek, check syscall bitness directly 2016-03-22 15:36:02 -07:00
f2fs f2fs: submit node page write bios when really required 2016-03-17 21:19:47 -07:00
fat fat: add config option to set UTF-8 mount option by default 2016-03-22 15:36:02 -07:00
freevxfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
fscache FS-Cache: Handle a write to the page immediately beyond the EOF marker 2015-11-11 02:11:02 -05:00
fuse fuse: return patrial success from fuse_direct_io() 2016-03-16 14:38:31 +01:00
gfs2 GFS2: merge window 2016-03-17 16:51:32 -07:00
hfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hfsplus wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hostfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hpfs hpfs: don't truncate the file when delete fails 2016-02-27 19:15:51 -05:00
hugetlbfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
isofs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
jbd2 jbd2: do not fail journal because of frozen_buffer allocation failure 2016-03-13 17:38:20 -04:00
jffs2 MTD updates for v4.6 2016-03-24 19:57:15 -07:00
jfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
kernfs Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-03-21 10:05:13 -07:00
lockd lockd: constify nlmsvc_binding structure 2016-01-07 10:10:50 -05:00
logfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
minix kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
ncpfs ncpfs: fix a braino in OOM handling in ncp_fill_cache() 2016-03-07 22:25:16 -05:00
nfs Various bugfixes, a RDMA update from Chuck Lever, and support for a new 2016-03-24 19:50:32 -07:00
nfs_common lockd: NLM grace period shouldn't block NFSv4 opens 2015-08-13 10:22:06 -04:00
nfsd Various bugfixes, a RDMA update from Chuck Lever, and support for a new 2016-03-24 19:50:32 -07:00
nilfs2 mm: introduce page reference manipulation functions 2016-03-17 15:09:34 -07:00
nls
notify fsnotify: turn fsnotify reaper thread into a workqueue job 2016-02-18 16:23:24 -08:00
ntfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ocfs2 ocfs2: extend enough credits for freeing one truncate record while replaying truncate records 2016-03-25 16:37:42 -07:00
omfs omfs: fix potential integer overflow in allocator 2015-05-28 18:25:19 -07:00
openpromfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
orangefs orangefs: fix orangefs_superblock locking 2016-03-26 07:22:00 -04:00
overlayfs ovl: cleanup unused var in rename2 2016-03-21 17:31:46 +01:00
proc Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-03-21 10:05:13 -07:00
pstore pstore: Add support for 64 Bit address space 2016-03-10 09:43:36 -08:00
qnx4 kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
qnx6 kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
quota Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2016-03-21 12:22:37 -07:00
ramfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
reiserfs quota: Add support for ->get_nextdqblk() for VFS quota 2016-02-09 13:05:23 +01:00
romfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
squashfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
sysfs platform/chrome: Branch for v4.4 2015-11-13 21:53:18 -08:00
sysv kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
tracefs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ubifs ubifs: Remove unused header 2016-03-20 21:37:46 +01:00
udf udf: Merge linux specific translation into CS0 conversion function 2016-02-09 13:05:23 +01:00
ufs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
xfs Various bugfixes, a RDMA update from Chuck Lever, and support for a new 2016-03-24 19:50:32 -07:00
Kconfig Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux 2016-03-26 12:59:04 -07:00
Kconfig.binfmt
Makefile Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux 2016-03-26 12:59:04 -07:00
aio.c mm: move ->mremap() from file_operations to vm_operations_struct 2015-09-04 16:54:41 -07:00
anon_inodes.c
attr.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
bad_inode.c fs/bad_inode.c: is_bad_inode can be boolean 2015-12-06 21:17:14 -05:00
binfmt_aout.c
binfmt_elf.c mm: ASLR: use get_random_long() 2016-02-27 10:28:52 -08:00
binfmt_elf_fdpic.c libnvdimm for 4.4: 2015-11-10 12:07:22 -08:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
binfmt_script.c
block_dev.c Merge branch 'for-4.6/core' of git://git.kernel.dk/linux-block 2016-03-18 16:43:11 -07:00
buffer.c mm: simplify lock_page_memcg() 2016-03-15 16:55:16 -07:00
char_dev.c chrdev: emit a warning when we go below dynamic major range 2016-03-29 10:11:44 -07:00
compat.c saner calling conventions for copy_mount_options() 2016-01-04 10:28:32 -05:00
compat_binfmt_elf.c
compat_ioctl.c Merge 4.5-rc4 into char-misc-next 2016-02-14 14:25:59 -08:00
coredump.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
dax.c xfs: Changes for 4.6-rc1 2016-03-21 11:53:05 -07:00
dcache.c dcache.c: new helper: __d_add() 2016-03-14 00:17:38 -04:00
dcookies.c
direct-io.c xfs: Changes for 4.6-rc1 2016-03-21 11:53:05 -07:00
drop_caches.c inode: convert inode_sb_list_lock to per-sb 2015-08-17 18:39:46 -04:00
eventfd.c eventfd: document lockless access in eventfd_poll 2016-03-22 15:36:02 -07:00
eventpoll.c timer: convert timer_slack_ns from unsigned long to u64 2016-03-17 15:09:34 -07:00
exec.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
fcntl.c fcntl: allow to set O_DIRECT flag on pipe 2016-01-09 02:55:37 -05:00
fhandle.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
file.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
file_table.c fs, file table: reinit files_stat.max_files after deferred memory initialisation 2015-08-07 04:39:40 +03:00
filesystems.c find_filesystem(): simplify comparison 2016-01-19 12:02:23 -05:00
fs-writeback.c writeback, cgroup: fix use of the wrong bdi_writeback which mismatches the inode 2016-03-20 09:44:20 -06:00
fs_pin.c
fs_struct.c
inode.c writeback: initialize inode members that track writeback history 2016-02-16 14:57:21 -07:00
internal.h Merge branch 'for-linus' into work.misc 2016-01-08 21:20:11 -05:00
ioctl.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
libfs.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
locks.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
mbcache.c mbcache: add reusable flag to cache entries 2016-02-22 22:44:04 -05:00
mount.h fs: use seq_open_private() for proc_mounts 2015-06-30 19:44:56 -07:00
mpage.c fs/mpage.c:mpage_readpages(): use lru_to_page() helper 2016-03-15 16:55:16 -07:00
namei.c kill dentry_unhash() 2016-03-14 00:16:33 -04:00
namespace.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
no-block.c
nsfs.c fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void 2015-09-11 15:21:34 -07:00
open.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-03-22 15:36:02 -07:00
pipe.c pipe: limit the per-user amount of pages allocated in pipes 2016-01-19 19:25:21 -05:00
pnode.c fs/pnode.c: treat zero mnt_group_id-s as unequal 2016-02-20 00:15:52 -05:00
pnode.h mnt: Clarify and correct the disconnect logic in umount_tree 2015-07-22 20:33:27 -05:00
posix_acl.c xattr handlers: Simplify list operation 2015-12-13 19:46:12 -05:00
proc_namespace.c vfs: show_vfsstat: do not ignore errors from show_devname method 2016-03-16 13:09:08 -04:00
read_write.c Merge branches 'work.lookups', 'work.misc' and 'work.preadv2' into for-next 2016-03-18 16:07:38 -04:00
readdir.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
select.c timer: convert timer_slack_ns from unsigned long to u64 2016-03-17 15:09:34 -07:00
seq_file.c fs, seqfile: always allow oom killer 2015-11-06 17:50:42 -08:00
signalfd.c signalfd: fix information leak in signalfd_copyinfo 2015-08-07 04:39:40 +03:00
splice.c Merge branches 'work.lookups', 'work.misc' and 'work.preadv2' into for-next 2016-03-18 16:07:38 -04:00
stack.c
stat.c fs/stat.c: drop the last new_valid_dev check 2016-01-16 11:17:23 -08:00
statfs.c
super.c writeback: flush inode cgroup wb switches instead of pinning super_block 2016-03-03 14:42:50 -07:00
sync.c fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE writeback 2015-11-06 17:50:42 -08:00
timerfd.c timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
userfaultfd.c userfaultfd: don't block on the last VM updates at exit time 2016-03-02 09:03:18 -08:00
utimes.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
xattr.c xattr handlers: plug a lock leak in simple_xattr_list 2016-02-20 00:15:51 -05:00