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Michal Hocko 2a95ea6c0d procfs: do not overflow get_{idle,iowait}_time for nohz 
Since commit a25cac5198 ("proc: Consider NO_HZ when printing idle and
iowait times") we are reporting idle/io_wait time also while a CPU is
tickless.  We rely on get_{idle,iowait}_time functions to retrieve
proper data.

These functions, however, use usecs_to_cputime to translate micro
seconds time to cputime64_t.  This is just an alias to usecs_to_jiffies
which reduces the data type from u64 to unsigned int and also checks
whether the given parameter overflows jiffies_to_usecs(MAX_JIFFY_OFFSET)
and returns MAX_JIFFY_OFFSET in that case.

When we overflow depends on CONFIG_HZ but especially for CONFIG_HZ_300
it is quite low (1431649781) so we are getting MAX_JIFFY_OFFSET for
>3000s! until we overflow unsigned int.  Just for reference
CONFIG_HZ_100 has an overflow window around 20s, CONFIG_HZ_250 ~8s and
CONFIG_HZ_1000 ~2s.

This results in a bug when people saw [h]top going mad reporting 100%
CPU usage even though there was basically no CPU load.  The reason was
simply that /proc/stat stopped reporting idle/io_wait changes (and
reported MAX_JIFFY_OFFSET) and so the only change happening was for user
system time.

Let's use nsecs_to_jiffies64 instead which doesn't reduce the precision
to 32b type and it is much more appropriate for cumulative time values
(unlike usecs_to_jiffies which intended for timeout calculations).

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Tested-by: Artem S. Tashkinov <t.artem@mailcity.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-09 07:50:29 -08:00
..
9p filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
adfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
affs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
afs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
autofs4 filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
befs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
bfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2011-12-08 13:18:59 -08:00
cachefiles kill useless checks for sb->s_op == NULL 2011-07-20 01:44:21 -04:00
ceph ceph: initialize root dentry 2011-11-11 09:50:17 -08:00
cifs Merge git://git.samba.org/sfrench/cifs-2.6 2011-11-07 09:56:22 -08:00
coda filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
configfs doc: fix broken references 2011-09-27 18:08:04 +02:00
cramfs cramfs: get_cramfs_inode() returns ERR_PTR() on failure 2011-07-17 23:22:02 -04:00
debugfs debugfs: Fix a comment mistake 2011-08-22 17:41:48 -07:00
devpts filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
dlm Merge branch 'for-3.1' of git://linux-nfs.org/~bfields/linux 2011-07-25 22:49:19 -07:00
ecryptfs eCryptfs: Extend array bounds for all filename chars 2011-11-23 15:43:53 -06:00
efs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
exofs Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
exportfs
ext2 Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue 2011-11-02 11:41:01 -07:00
ext3 Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue 2011-11-02 11:41:01 -07:00
ext4 ext4: fix racy use-after-free in ext4_end_io_dio() 2011-11-24 19:22:24 -05:00
fat filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
freevxfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
fscache FS-Cache: Fix __fscache_uncache_all_inode_pages()'s outer loop 2011-07-21 10:59:16 -07:00
fuse Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
gfs2 Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
hfs hfs: add sanity check for file name length 2011-11-15 14:29:42 -02:00
hfsplus filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
hostfs Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue 2011-11-02 11:41:01 -07:00
hpfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
hppfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
hugetlbfs filesystems: add missing nlink wrappers 2011-11-02 12:53:43 +01:00
isofs Merge branch 'akpm' (Andrew's incoming - part two) 2011-11-02 16:07:27 -07:00
jbd jbd/jbd2: validate sb->s_first in journal_get_superblock() 2011-11-01 19:04:59 -04:00
jbd2 jbd2: Unify log messages in jbd2 code 2011-11-01 19:09:18 -04:00
jffs2 Merge git://git.infradead.org/mtd-2.6 2011-11-07 09:11:16 -08:00
jfs Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
lockd SUNRPC: Replace svc_addr_u by sockaddr_storage 2011-09-14 08:21:48 -04:00
logfs Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
minix minixfs: kill manual hweight(), simplify 2011-11-19 11:13:28 -05:00
ncpfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
nfs Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/linux-nfs 2011-11-22 08:54:15 -08:00
nfs_common
nfsd Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
nilfs2 filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
nls
notify atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
ntfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
ocfs2 Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 2011-12-01 14:55:34 -08:00
omfs omfs: fix (mode & S_IFDIR) abuse 2011-07-26 13:05:28 -04:00
openpromfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
partitions treewide: use __printf not __attribute__((format(printf,...))) 2011-10-31 17:30:54 -07:00
proc procfs: do not overflow get_{idle,iowait}_time for nohz 2011-12-09 07:50:29 -08:00
pstore pstore: pass allocated memory region back to caller 2011-11-17 12:58:07 -08:00
qnx4 filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
quota Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux 2011-11-06 19:02:23 -08:00
ramfs ramfs: remove module leftovers 2011-11-02 16:06:58 -07:00
reiserfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
romfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
squashfs Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next 2011-11-04 16:48:37 -07:00
sysfs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
sysv filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
ubifs Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6 2011-11-07 08:52:19 -08:00
udf Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue 2011-11-02 11:41:01 -07:00
ufs filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
xfs xfs: fix the logspace waiting algorithm 2011-12-06 14:19:47 -06:00
aio.c aio: allocate kiocbs in batches 2011-11-02 16:07:03 -07:00
anon_inodes.c vfs: dont chain pipe/anon/socket on superblock s_inodes list 2011-07-26 12:57:09 -04:00
attr.c Merge branch 'next-evm' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/ima-2.6 into next 2011-08-09 10:31:03 +10:00
bad_inode.c fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers 2011-07-20 20:47:59 -04:00
binfmt_aout.c
binfmt_elf_fdpic.c consolidate BINPRM_FLAGS_ENFORCE_NONDUMP handling 2011-07-20 01:43:10 -04:00
binfmt_elf.c binfmt_elf: fix PIE execution with randomization disabled 2011-11-02 16:06:58 -07:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c filesystems: add missing nlink wrappers 2011-11-02 12:53:43 +01:00
binfmt_script.c
binfmt_som.c
bio-integrity.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
bio.c bio: change some signed vars to unsigned 2011-11-16 09:21:50 +01:00
block_dev.c Merge branch 'for-3.2/drivers' of git://git.kernel.dk/linux-block 2011-11-04 17:22:14 -07:00
buffer.c Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux 2011-11-06 19:02:23 -08:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c compat_ioctl: add compat handler for PPPIOCGL2TPSTATS 2011-08-07 22:24:41 -07:00
compat.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
dcache.c fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API 2011-12-06 23:57:18 -05:00
dcookies.c
direct-io.c direct-io: merge direct_io_walker into __blockdev_direct_IO 2011-10-28 14:58:58 +02:00
drop_caches.c
eventfd.c
eventpoll.c epoll: fix spurious lockdep warnings 2011-10-31 17:30:57 -07:00
exec.c oom: remove oom_disable_count 2011-10-31 17:30:45 -07:00
fcntl.c
fhandle.c
fifo.c
file_table.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
file.c
filesystems.c
fs_struct.c
fs-writeback.c writeback: Add a 'reason' to wb_writeback_work 2011-10-31 00:33:36 +08:00
generic_acl.c switch posix_acl_equiv_mode() to umode_t * 2011-08-01 02:10:06 -04:00
inode.c vfs: protect i_nlink 2011-11-02 12:53:43 +01:00
internal.h superblock: move pin_sb_for_writeback() to fs/super.c 2011-07-20 01:44:38 -04:00
ioctl.c
ioprio.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
Kconfig tmpfs: add "tmpfs" to the Kconfig prompt to make it obvious. 2011-10-31 17:30:45 -07:00
Kconfig.binfmt
libfs.c filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
locks.c Merge branch 'for-3.2' of git://linux-nfs.org/~bfields/linux 2011-10-25 15:42:01 +02:00
Makefile fs/Makefile: Stupid typo breakage of exofs inclusion 2011-10-27 08:36:51 +02:00
mbcache.c
mpage.c
namei.c VFS: we need to set LOOKUP_JUMPED on mountpoint crossing 2011-11-07 14:58:06 -08:00
namespace.c fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API 2011-12-06 23:57:18 -05:00
no-block.c
open.c leases: fix write-open/read-lease race 2011-10-28 14:59:00 +02:00
pipe.c fs/pipe.c: add ->statfs callback for pipefs 2011-10-31 17:30:51 -07:00
pnode.c
pnode.h
posix_acl.c vfs: pass all mask flags check_acl and posix_acl_permission 2011-10-28 14:58:54 +02:00
read_write.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
read_write.h
readdir.c
select.c
seq_file.c fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API 2011-12-06 23:57:18 -05:00
signalfd.c
splice.c tmpfs: clone shmem_file_splice_read() 2011-07-25 20:57:11 -07:00
stack.c filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
stat.c readlinkat: ensure we return ENOENT for the empty pathname for normal lookups 2011-11-02 12:53:42 +01:00
statfs.c VFS: fix statfs() automounter semantics regression 2011-11-04 18:15:59 -07:00
super.c vfs: ignore error on forced remount 2011-11-02 12:53:42 +01:00
sync.c writeback: Add a 'reason' to wb_writeback_work 2011-10-31 00:33:36 +08:00
timerfd.c
utimes.c
xattr_acl.c
xattr.c evm: evm_inode_post_removexattr 2011-07-18 12:29:43 -04:00