From: akpm@linux-foundation.org Subject: + revert-percpu_counter-new-function-percpu_counter_sum_and_set.patch added to -mm tree Date: Sat, 06 Dec 2008 20:22:52 -0800 Message-ID: <200812070422.mB74Mqgb012946@imap1.linux-foundation.org> Cc: akpm@linux-foundation.org, a.p.zijlstra@chello.nl, cmm@us.ibm.com, dada1@cosmosbay.com, davem@davemloft.net, linux-ext4@vger.kernel.org To: mm-commits@vger.kernel.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:57393 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753544AbYLGEXG (ORCPT ); Sat, 6 Dec 2008 23:23:06 -0500 Sender: linux-ext4-owner@vger.kernel.org List-ID: 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 Revert commit e8ced39d5e8911c662d4d69a342b9d053eaaac4e Author: Mingming Cao 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 Cc: "David S. Miller" Cc: Peter Zijlstra Cc: Mingming Cao Cc: Signed-off-by: Andrew Morton --- 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 akpm@linux-foundation.org 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