Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1521062

[PATCH 3.2 003/152] sched/cputime: Fix prev steal time accouting during CPU hotplug

Show all headers | View raw

3.2.84-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Wanpeng Li <wanpeng.li@hotmail.com>

commit 3d89e5478bf550a50c99e93adf659369798263b0 upstream.

Commit:

  e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")

... set rq->prev_* to 0 after a CPU hotplug comes back, in order to
fix the case where (after CPU hotplug) steal time is smaller than
rq->prev_steal_time.

However, this should never happen. Steal time was only smaller because of the
KVM-specific bug fixed by the previous patch.  Worse, the previous patch
triggers a bug on CPU hot-unplug/plug operation: because
rq->prev_steal_time is cleared, all of the CPU's past steal time will be
accounted again on hot-plug.

Since the root cause has been fixed, we can just revert commit e9532e69b8d1.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 'commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")'
Link: http://lkml.kernel.org/r/1465813966-3116-3-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2084,19 +2084,6 @@ EXPORT_SYMBOL_GPL(account_system_vtime);
 
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
-static inline void account_reset_rq(struct rq *rq)
-{
-#ifdef CONFIG_IRQ_TIME_ACCOUNTING
-	rq->prev_irq_time = 0;
-#endif
-#ifdef CONFIG_PARAVIRT
-	rq->prev_steal_time = 0;
-#endif
-#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
-	rq->prev_steal_time_rq = 0;
-#endif
-}
-
 #ifdef CONFIG_PARAVIRT
 static inline u64 steal_ticks(u64 steal)
 {
@@ -6869,7 +6856,6 @@ migration_call(struct notifier_block *nf
 
 	case CPU_UP_PREPARE:
 		rq->calc_load_update = calc_load_update;
-		account_reset_rq(rq);
 		break;
 
 	case CPU_ONLINE:

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 3.2 000/152] 3.2.84-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 070/152] cdc-acm: fix wrong pipe type on rx interrupt  xfers Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 108/152] frv: fix clear_user() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 088/152] ALSA: timer: fix NULL pointer dereference on  memory allocation failure Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 044/152] KEYS: 64-bit MIPS needs to use  compat_sys_keyctl for 32-bit userspace Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 009/152] ext4: check for extents that wrap around Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
    Re: [PATCH 3.2 009/152] ext4: check for extents that wrap around Vegard Nossum <vegard.nossum@oracle.com> - 2016-11-14 16:40 +0100
      Re: [PATCH 3.2 009/152] ext4: check for extents that wrap around Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 17:20 +0100
  [PATCH 3.2 101/152] asm-generic: make copy_from_user() zero the  destination properly Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 077/152] USB: serial: option: add WeTelecom WM-D200 Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 125/152] microblaze: fix __get_user() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 010/152] ext4: don't call ext4_should_journal_data()  on the journal inode Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 041/152] l2tp: Correctly return -EBADF from  pppol2tp_getname. Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 089/152] ALSA: timer: fix NULL pointer dereference in  read()/ioctl() race Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 045/152] drm/radeon: fix firmware info version checks Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 053/152] dm flakey: error READ bios during the  down_interval Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 030/152] crypto: scatterwalk - Fix test in  scatterwalk_done Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 131/152] openrisc: fix the fix of copy_from_user() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 066/152] arm: oabi compat: add missing access checks Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 112/152] mn10300: copy_from_user() should zero on  access_ok() failure... Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 037/152] nfs: don't create zero-length requests Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:10 +0100
  [PATCH 3.2 015/152] x86/quirks: Apply nvidia_bugs quirk only on  root bus Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 013/152] ALSA: ctl: Stop notification after disconnection Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 019/152] NFS: Don't drop CB requests with invalid  principals Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 007/152] usb: renesas_usbhs: protect the CFIFOSEL  setting in usbhsg_ep_enable() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 021/152] Bluetooth: Add support of 13d3:3490 AR3012 device Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 003/152] sched/cputime: Fix prev steal time accouting  during CPU hotplug Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 029/152] Bluetooth: Fix l2cap_sock_setsockopt() with  optname BT_RCVMTU Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 008/152] Input: xpad - validate USB endpoint count  during probe Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 036/152] MIPS: RM7000: Double locking bug in  rm7k_tc_disable() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 018/152] svc: Avoid garbage replies when pc_func()  returns rpc_drop_reply Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 006/152] usb: renesas_usbhs: fix NULL pointer  dereference in xfer_work() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 035/152] tty/vt/keyboard: fix OOB access in  do_compute_shiftstate() Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  [PATCH 3.2 012/152] drm/radeon: Poll for both connect/disconnect  on analog connectors Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 04:20 +0100
  Re: [PATCH 3.2 000/152] 3.2.84-rc1 review Guenter Roeck <linux@roeck-us.net> - 2016-11-14 06:50 +0100
    Re: [PATCH 3.2 000/152] 3.2.84-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2016-11-14 18:20 +0100

csiph-web