The patch titled
revert "percpu_counter: new function percpu_counter_sum_and_set"
has been added to the -mm tree. Its filename is
revert-percpu_counter-new-function-percpu_counter_sum_and_set.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: revert "percpu_counter: new function percpu_counter_sum_and_set"
From: Andrew Morton <[email protected]>
Revert
commit e8ced39d5e8911c662d4d69a342b9d053eaaac4e
Author: Mingming Cao <[email protected]>
Date: Fri Jul 11 19:27:31 2008 -0400
percpu_counter: new function percpu_counter_sum_and_set
As described in
revert "percpu counter: clean up percpu_counter_sum_and_set()"
the new percpu_counter_sum_and_set() is racy against updates to the
cpu-local accumulators on other CPUs. Revert that change.
This means that ext4 will be slow again. But correct.
Reported-by: Eric Dumazet <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Mingming Cao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/ext4/balloc.c | 4 ++--
include/linux/percpu_counter.h | 12 +++---------
lib/percpu_counter.c | 7 +------
3 files changed, 6 insertions(+), 17 deletions(-)
diff -puN fs/ext4/balloc.c~revert-percpu_counter-new-function-percpu_counter_sum_and_set fs/ext4/balloc.c
--- a/fs/ext4/balloc.c~revert-percpu_counter-new-function-percpu_counter_sum_and_set
+++ a/fs/ext4/balloc.c
@@ -609,8 +609,8 @@ int ext4_has_free_blocks(struct ext4_sb_
if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
EXT4_FREEBLOCKS_WATERMARK) {
- free_blocks = percpu_counter_sum_and_set(fbc);
- dirty_blocks = percpu_counter_sum_and_set(dbc);
+ free_blocks = percpu_counter_sum_positive(fbc);
+ dirty_blocks = percpu_counter_sum_positive(dbc);
if (dirty_blocks < 0) {
printk(KERN_CRIT "Dirty block accounting "
"went wrong %lld\n",
diff -puN include/linux/percpu_counter.h~revert-percpu_counter-new-function-percpu_counter_sum_and_set include/linux/percpu_counter.h
--- a/include/linux/percpu_counter.h~revert-percpu_counter-new-function-percpu_counter_sum_and_set
+++ a/include/linux/percpu_counter.h
@@ -35,7 +35,7 @@ int percpu_counter_init_irq(struct percp
void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
-s64 __percpu_counter_sum(struct percpu_counter *fbc, int set);
+s64 __percpu_counter_sum(struct percpu_counter *fbc);
static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
@@ -44,19 +44,13 @@ static inline void percpu_counter_add(st
static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
- s64 ret = __percpu_counter_sum(fbc, 0);
+ s64 ret = __percpu_counter_sum(fbc);
return ret < 0 ? 0 : ret;
}
-static inline s64 percpu_counter_sum_and_set(struct percpu_counter *fbc)
-{
- return __percpu_counter_sum(fbc, 1);
-}
-
-
static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
- return __percpu_counter_sum(fbc, 0);
+ return __percpu_counter_sum(fbc);
}
static inline s64 percpu_counter_read(struct percpu_counter *fbc)
diff -puN lib/percpu_counter.c~revert-percpu_counter-new-function-percpu_counter_sum_and_set lib/percpu_counter.c
--- a/lib/percpu_counter.c~revert-percpu_counter-new-function-percpu_counter_sum_and_set
+++ a/lib/percpu_counter.c
@@ -52,7 +52,7 @@ EXPORT_SYMBOL(__percpu_counter_add);
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
*/
-s64 __percpu_counter_sum(struct percpu_counter *fbc, int set)
+s64 __percpu_counter_sum(struct percpu_counter *fbc)
{
s64 ret;
int cpu;
@@ -62,12 +62,7 @@ s64 __percpu_counter_sum(struct percpu_c
for_each_online_cpu(cpu) {
s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
ret += *pcount;
- if (set)
- *pcount = 0;
}
- if (set)
- fbc->count = ret;
-
spin_unlock(&fbc->lock);
return ret;
}
_
Patches currently in -mm which might be from [email protected] are
origin.patch
mm-backing-devc-remove-recently-added-warn_on.patch
revert-percpu-counter-clean-up-percpu_counter_sum_and_set.patch
revert-percpu_counter-new-function-percpu_counter_sum_and_set.patch
ksym_symbol_len-fixes.patch
mm-remove-the-might_sleep-from-lock_page.patch
make-linx-next-apply.patch
linux-next.patch
next-remove-localversion.patch
tick-schedc-suppress-needless-timer-reprogramming.patch
linux-timexh-cleanup-for-userspace.patch
drivers-input-touchscreen-ucb1400_tsc-needs-gpio.patch
netdev-smc911x-fix-for-driver-resume-cleanup.patch
backlight-catch-invalid-input.patch
pci-uninline-pci_ioremap_bar.patch
drivers-char-cycladesc-cy_pci_probe-fix-error-path.patch
scsi-dpt_i2o-is-bust-on-ia64.patch
mm-invoke-oom-killer-from-page-fault-fix.patch
mm-invoke-oom-killer-from-page-fault-fix-fix-2.patch
mm-write_cache_pages-more-terminate-quickly.patch
swapfile-change-discard-pgoff_t-to-sector_t-fix.patch
fs-truncate-blocks-outside-i_size-after-o_direct-write-error-fix.patch
vmscan-shrink_active_list-reduce-lru_lock-hold-time.patch
init-properly-placing-noinline-keyword.patch
add-pr_prefix-to-pr_xyz-macros-checkpatch-fixes.patch
poll-allow-f_op-poll-to-sleep-take6.patch
binfmtsh-include-listh-fix.patch
max3100-spi-uart-driver-select-serial_core-fix.patch
spi_gpio-driver-cleanups.patch
kprobes-support-probing-module-__exit-function-fix.patch
kprobes-support-probing-module-__exit-function-fix-2.patch
rtc-au1000-on-chip-counter0-as-rtc-driver-fix.patch
memcg-introduce-charge-commit-cancel-style-of-functions-fix.patch
memcg-new-force_empty-to-free-pages-under-group-fix-fix.patch
memcg-swap-cgroup-for-remembering-usage.patch
memory-cgroup-resource-counters-for-hierarchy-v4-checkpatch-fixes.patch
memory-cgroup-hierarchical-reclaim-v4-checkpatch-fixes.patch
memcg-avoid-unnecessary-system-wide-oom-killer-fix.patch
edac-struct-device-replace-bus_id-with-dev_name-dev_set_name-checkpatch-fixes.patch
edac-x38-use-the-architectures-readq-function-fix.patch
parport-ieee1284-use-del_timer_sync-in-parport_wait_event-checkpatch-fixes.patch
romfs-romfs_iget-unsigned-ino-=-0-is-always-true-checkpatch-fixes.patch
filesystem-freeze-implement-generic-freeze-feature-fix.patch
ldisc-n_tty-export-all-n_tty-ldisc-methods-fix.patch
nilfs2-inode-operations-fix.patch
nilfs2-pathname-operations-fix.patch
nilfs2-super-block-operations-fix.patch
reiser4.patch
reiser4-tree_lock-fixes.patch
reiser4-tree_lock-fixes-fix.patch
reiser4-semaphore-fix.patch
slb-drop-kmem-cache-argument-from-constructor-reiser4.patch
reiser4-suid.patch
reiser4-track-upstream-changes.patch
reiser4-remove-simple_prepare_write-usage-checkpatch-fixes.patch
nr_blockdev_pages-in_interrupt-warning.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
shrink_slab-handle-bad-shrinkers.patch
getblk-handle-2tb-devices.patch
getblk-handle-2tb-devices-fix.patch
undeprecate-pci_find_device.patch
notify_change-callers-must-hold-i_mutex.patch
drivers-net-bonding-bond_sysfsc-suppress-uninitialized-var-warning.patch
w1-build-fix.patch