[1/3] mm, meminit: Recalculate pcpu batch and high limits after init completes
diff mbox series

Message ID 20191021094808.28824-2-mgorman@techsingularity.net
State New
Headers show
Series
  • Recalculate per-cpu page allocator batch and high limits after deferred meminit v2
Related show

Commit Message

Mel Gorman Oct. 21, 2019, 9:48 a.m. UTC
Deferred memory initialisation updates zone->managed_pages during
the initialisation phase but before that finishes, the per-cpu page
allocator (pcpu) calculates the number of pages allocated/freed in
batches as well as the maximum number of pages allowed on a per-cpu list.
As zone->managed_pages is not up to date yet, the pcpu initialisation
calculates inappropriately low batch and high values.

This increases zone lock contention quite severely in some cases with the
degree of severity depending on how many CPUs share a local zone and the
size of the zone. A private report indicated that kernel build times were
excessive with extremely high system CPU usage. A perf profile indicated
that a large chunk of time was lost on zone->lock contention.

This patch recalculates the pcpu batch and high values after deferred
initialisation completes for every populated zone in the system. It
was tested on a 2-socket AMD EPYC 2 machine using a kernel compilation
workload -- allmodconfig and all available CPUs.

mmtests configuration: config-workload-kernbench-max
Configuration was modified to build on a fresh XFS partition.

kernbench
                                5.4.0-rc3              5.4.0-rc3
                                  vanilla           resetpcpu-v2
Amean     user-256    13249.50 (   0.00%)    16401.31 * -23.79%*
Amean     syst-256    14760.30 (   0.00%)     4448.39 *  69.86%*
Amean     elsp-256      162.42 (   0.00%)      119.13 *  26.65%*
Stddev    user-256       42.97 (   0.00%)       19.15 (  55.43%)
Stddev    syst-256      336.87 (   0.00%)        6.71 (  98.01%)
Stddev    elsp-256        2.46 (   0.00%)        0.39 (  84.03%)

                   5.4.0-rc3    5.4.0-rc3
                     vanilla resetpcpu-v2
Duration User       39766.24     49221.79
Duration System     44298.10     13361.67
Duration Elapsed      519.11       388.87

The patch reduces system CPU usage by 69.86% and total build time by
26.65%. The variance of system CPU usage is also much reduced.

Before, this was the breakdown of batch and high values over all zones was.

    256               batch: 1
    256               batch: 63
    512               batch: 7
    256               high:  0
    256               high:  378
    512               high:  42

512 pcpu pagesets had a batch limit of 7 and a high limit of 42. After the patch

    256               batch: 1
    768               batch: 63
    256               high:  0
    768               high:  378

Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/page_alloc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Michal Hocko Oct. 21, 2019, 10:27 a.m. UTC | #1
On Mon 21-10-19 10:48:06, Mel Gorman wrote:
> Deferred memory initialisation updates zone->managed_pages during
> the initialisation phase but before that finishes, the per-cpu page
> allocator (pcpu) calculates the number of pages allocated/freed in
> batches as well as the maximum number of pages allowed on a per-cpu list.
> As zone->managed_pages is not up to date yet, the pcpu initialisation
> calculates inappropriately low batch and high values.
> 
> This increases zone lock contention quite severely in some cases with the
> degree of severity depending on how many CPUs share a local zone and the
> size of the zone. A private report indicated that kernel build times were
> excessive with extremely high system CPU usage. A perf profile indicated
> that a large chunk of time was lost on zone->lock contention.
> 
> This patch recalculates the pcpu batch and high values after deferred
> initialisation completes for every populated zone in the system. It
> was tested on a 2-socket AMD EPYC 2 machine using a kernel compilation
> workload -- allmodconfig and all available CPUs.
> 
> mmtests configuration: config-workload-kernbench-max
> Configuration was modified to build on a fresh XFS partition.
> 
> kernbench
>                                 5.4.0-rc3              5.4.0-rc3
>                                   vanilla           resetpcpu-v2
> Amean     user-256    13249.50 (   0.00%)    16401.31 * -23.79%*
> Amean     syst-256    14760.30 (   0.00%)     4448.39 *  69.86%*
> Amean     elsp-256      162.42 (   0.00%)      119.13 *  26.65%*
> Stddev    user-256       42.97 (   0.00%)       19.15 (  55.43%)
> Stddev    syst-256      336.87 (   0.00%)        6.71 (  98.01%)
> Stddev    elsp-256        2.46 (   0.00%)        0.39 (  84.03%)
> 
>                    5.4.0-rc3    5.4.0-rc3
>                      vanilla resetpcpu-v2
> Duration User       39766.24     49221.79
> Duration System     44298.10     13361.67
> Duration Elapsed      519.11       388.87
> 
> The patch reduces system CPU usage by 69.86% and total build time by
> 26.65%. The variance of system CPU usage is also much reduced.
> 
> Before, this was the breakdown of batch and high values over all zones was.
> 
>     256               batch: 1
>     256               batch: 63
>     512               batch: 7
>     256               high:  0
>     256               high:  378
>     512               high:  42
> 
> 512 pcpu pagesets had a batch limit of 7 and a high limit of 42. After the patch
> 
>     256               batch: 1
>     768               batch: 63
>     256               high:  0
>     768               high:  378
> 
> Cc: stable@vger.kernel.org # v4.1+
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/page_alloc.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c0b2e0306720..f972076d0f6b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1947,6 +1947,14 @@ void __init page_alloc_init_late(void)
>  	/* Block until all are initialised */
>  	wait_for_completion(&pgdat_init_all_done_comp);
>  
> +	/*
> +	 * The number of managed pages has changed due to the initialisation
> +	 * so the pcpu batch and high limits needs to be updated or the limits
> +	 * will be artificially small.
> +	 */
> +	for_each_populated_zone(zone)
> +		zone_pcp_update(zone);
> +
>  	/*
>  	 * We initialized the rest of the deferred pages.  Permanently disable
>  	 * on-demand struct page initialization.
> -- 
> 2.16.4
Vlastimil Babka Oct. 21, 2019, 11:42 a.m. UTC | #2
On 10/21/19 11:48 AM, Mel Gorman wrote:
> Deferred memory initialisation updates zone->managed_pages during
> the initialisation phase but before that finishes, the per-cpu page
> allocator (pcpu) calculates the number of pages allocated/freed in
> batches as well as the maximum number of pages allowed on a per-cpu list.
> As zone->managed_pages is not up to date yet, the pcpu initialisation
> calculates inappropriately low batch and high values.
> 
> This increases zone lock contention quite severely in some cases with the
> degree of severity depending on how many CPUs share a local zone and the
> size of the zone. A private report indicated that kernel build times were
> excessive with extremely high system CPU usage. A perf profile indicated
> that a large chunk of time was lost on zone->lock contention.
> 
> This patch recalculates the pcpu batch and high values after deferred
> initialisation completes for every populated zone in the system. It
> was tested on a 2-socket AMD EPYC 2 machine using a kernel compilation
> workload -- allmodconfig and all available CPUs.
> 
> mmtests configuration: config-workload-kernbench-max
> Configuration was modified to build on a fresh XFS partition.
> 
> kernbench
>                                 5.4.0-rc3              5.4.0-rc3
>                                   vanilla           resetpcpu-v2
> Amean     user-256    13249.50 (   0.00%)    16401.31 * -23.79%*
> Amean     syst-256    14760.30 (   0.00%)     4448.39 *  69.86%*
> Amean     elsp-256      162.42 (   0.00%)      119.13 *  26.65%*
> Stddev    user-256       42.97 (   0.00%)       19.15 (  55.43%)
> Stddev    syst-256      336.87 (   0.00%)        6.71 (  98.01%)
> Stddev    elsp-256        2.46 (   0.00%)        0.39 (  84.03%)
> 
>                    5.4.0-rc3    5.4.0-rc3
>                      vanilla resetpcpu-v2
> Duration User       39766.24     49221.79
> Duration System     44298.10     13361.67
> Duration Elapsed      519.11       388.87
> 
> The patch reduces system CPU usage by 69.86% and total build time by
> 26.65%. The variance of system CPU usage is also much reduced.
> 
> Before, this was the breakdown of batch and high values over all zones was.
> 
>     256               batch: 1
>     256               batch: 63
>     512               batch: 7
>     256               high:  0
>     256               high:  378
>     512               high:  42
> 
> 512 pcpu pagesets had a batch limit of 7 and a high limit of 42. After the patch
> 
>     256               batch: 1
>     768               batch: 63
>     256               high:  0
>     768               high:  378
> 
> Cc: stable@vger.kernel.org # v4.1+
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/page_alloc.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c0b2e0306720..f972076d0f6b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1947,6 +1947,14 @@ void __init page_alloc_init_late(void)
>  	/* Block until all are initialised */
>  	wait_for_completion(&pgdat_init_all_done_comp);
>  
> +	/*
> +	 * The number of managed pages has changed due to the initialisation
> +	 * so the pcpu batch and high limits needs to be updated or the limits
> +	 * will be artificially small.
> +	 */
> +	for_each_populated_zone(zone)
> +		zone_pcp_update(zone);
> +
>  	/*
>  	 * We initialized the rest of the deferred pages.  Permanently disable
>  	 * on-demand struct page initialization.
>
Qian Cai Oct. 21, 2019, 2:01 p.m. UTC | #3
> On Oct 21, 2019, at 5:48 AM, Mel Gorman <mgorman@techsingularity.net> wrote:
> 
> Deferred memory initialisation updates zone->managed_pages during
> the initialisation phase but before that finishes, the per-cpu page
> allocator (pcpu) calculates the number of pages allocated/freed in
> batches as well as the maximum number of pages allowed on a per-cpu list.
> As zone->managed_pages is not up to date yet, the pcpu initialisation
> calculates inappropriately low batch and high values.
> 
> This increases zone lock contention quite severely in some cases with the
> degree of severity depending on how many CPUs share a local zone and the
> size of the zone. A private report indicated that kernel build times were
> excessive with extremely high system CPU usage. A perf profile indicated
> that a large chunk of time was lost on zone->lock contention.
> 
> This patch recalculates the pcpu batch and high values after deferred
> initialisation completes for every populated zone in the system. It
> was tested on a 2-socket AMD EPYC 2 machine using a kernel compilation
> workload -- allmodconfig and all available CPUs.
> 
> mmtests configuration: config-workload-kernbench-max
> Configuration was modified to build on a fresh XFS partition.
> 
> kernbench
>                                5.4.0-rc3              5.4.0-rc3
>                                  vanilla           resetpcpu-v2
> Amean     user-256    13249.50 (   0.00%)    16401.31 * -23.79%*
> Amean     syst-256    14760.30 (   0.00%)     4448.39 *  69.86%*
> Amean     elsp-256      162.42 (   0.00%)      119.13 *  26.65%*
> Stddev    user-256       42.97 (   0.00%)       19.15 (  55.43%)
> Stddev    syst-256      336.87 (   0.00%)        6.71 (  98.01%)
> Stddev    elsp-256        2.46 (   0.00%)        0.39 (  84.03%)
> 
>                   5.4.0-rc3    5.4.0-rc3
>                     vanilla resetpcpu-v2
> Duration User       39766.24     49221.79
> Duration System     44298.10     13361.67
> Duration Elapsed      519.11       388.87
> 
> The patch reduces system CPU usage by 69.86% and total build time by
> 26.65%. The variance of system CPU usage is also much reduced.
> 
> Before, this was the breakdown of batch and high values over all zones was.
> 
>    256               batch: 1
>    256               batch: 63
>    512               batch: 7
>    256               high:  0
>    256               high:  378
>    512               high:  42
> 
> 512 pcpu pagesets had a batch limit of 7 and a high limit of 42. After the patch
> 
>    256               batch: 1
>    768               batch: 63
>    256               high:  0
>    768               high:  378
> 
> Cc: stable@vger.kernel.org # v4.1+
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> ---
> mm/page_alloc.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c0b2e0306720..f972076d0f6b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1947,6 +1947,14 @@ void __init page_alloc_init_late(void)
> 	/* Block until all are initialised */
> 	wait_for_completion(&pgdat_init_all_done_comp);
> 
> +	/*
> +	 * The number of managed pages has changed due to the initialisation
> +	 * so the pcpu batch and high limits needs to be updated or the limits
> +	 * will be artificially small.
> +	 */
> +	for_each_populated_zone(zone)
> +		zone_pcp_update(zone);
> +
> 	/*
> 	 * We initialized the rest of the deferred pages.  Permanently disable
> 	 * on-demand struct page initialization.
> -- 
> 2.16.4
> 
> 

Warnings from linux-next,

[   14.265911][  T659] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
[   14.265992][  T659] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 659, name: pgdatinit8
[   14.266044][  T659] 1 lock held by pgdatinit8/659:
[   14.266075][  T659]  #0: c000201ffca87b40 (&(&pgdat->node_size_lock)->rlock){....}, at: deferred_init_memmap+0xc4/0x26c
[   14.266160][  T659] irq event stamp: 26
[   14.266194][  T659] hardirqs last  enabled at (25): [<c000000000950584>] _raw_spin_unlock_irq+0x44/0x80
[   14.266246][  T659] hardirqs last disabled at (26): [<c0000000009502ec>] _raw_spin_lock_irqsave+0x3c/0xa0
[   14.266299][  T659] softirqs last  enabled at (0): [<c0000000000ff8d0>] copy_process+0x720/0x19b0
[   14.266339][  T659] softirqs last disabled at (0): [<0000000000000000>] 0x0
[   14.266400][  T659] CPU: 64 PID: 659 Comm: pgdatinit8 Not tainted 5.4.0-rc4-next-20191021 #1
[   14.266462][  T659] Call Trace:
[   14.266494][  T659] [c00000003d8efae0] [c000000000921cf4] dump_stack+0xe8/0x164 (unreliable)
[   14.266538][  T659] [c00000003d8efb30] [c000000000157c54] ___might_sleep+0x334/0x370
[   14.266577][  T659] [c00000003d8efbb0] [c00000000094a784] __mutex_lock+0x84/0xb20
[   14.266627][  T659] [c00000003d8efcc0] [c000000000954038] zone_pcp_update+0x34/0x64
[   14.266677][  T659] [c00000003d8efcf0] [c000000000b9e6bc] deferred_init_memmap+0x1b8/0x26c
[   14.266740][  T659] [c00000003d8efdb0] [c000000000149528] kthread+0x1a8/0x1b0
[   14.266792][  T659] [c00000003d8efe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74
[   14.268288][  T659] node 8 initialised, 1879186 pages in 12200ms
[   14.268527][  T659] pgdatinit8 (659) used greatest stack depth: 27984 bytes left
[   15.589983][  T658] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
[   15.590041][  T658] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 658, name: pgdatinit0
[   15.590078][  T658] 1 lock held by pgdatinit0/658:
[   15.590108][  T658]  #0: c000001fff5c7b40 (&(&pgdat->node_size_lock)->rlock){....}, at: deferred_init_memmap+0xc4/0x26c
[   15.590192][  T658] irq event stamp: 18
[   15.590224][  T658] hardirqs last  enabled at (17): [<c000000000950654>] _raw_spin_unlock_irqrestore+0x94/0xd0
[   15.590283][  T658] hardirqs last disabled at (18): [<c0000000009502ec>] _raw_spin_lock_irqsave+0x3c/0xa0
[   15.590332][  T658] softirqs last  enabled at (0): [<c0000000000ff8d0>] copy_process+0x720/0x19b0
[   15.590379][  T658] softirqs last disabled at (0): [<0000000000000000>] 0x0
[   15.590414][  T658] CPU: 8 PID: 658 Comm: pgdatinit0 Tainted: G        W         5.4.0-rc4-next-20191021 #1
[   15.590460][  T658] Call Trace:
[   15.590491][  T658] [c00000003d8cfae0] [c000000000921cf4] dump_stack+0xe8/0x164 (unreliable)
[   15.590541][  T658] [c00000003d8cfb30] [c000000000157c54] ___might_sleep+0x334/0x370
[   15.590588][  T658] [c00000003d8cfbb0] [c00000000094a784] __mutex_lock+0x84/0xb20
[   15.590643][  T658] [c00000003d8cfcc0] [c000000000954038] zone_pcp_update+0x34/0x64
[   15.590689][  T658] [c00000003d8cfcf0] [c000000000b9e6bc] deferred_init_memmap+0x1b8/0x26c
[   15.590739][  T658] [c00000003d8cfdb0] [c000000000149528] kthread+0x1a8/0x1b0
[   15.590790][  T658] [c00000003d8cfe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74
Michal Hocko Oct. 21, 2019, 2:12 p.m. UTC | #4
On Mon 21-10-19 10:01:24, Qian Cai wrote:
> 
> 
> > On Oct 21, 2019, at 5:48 AM, Mel Gorman <mgorman@techsingularity.net> wrote:
i[...]
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index c0b2e0306720..f972076d0f6b 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -1947,6 +1947,14 @@ void __init page_alloc_init_late(void)
> > 	/* Block until all are initialised */
> > 	wait_for_completion(&pgdat_init_all_done_comp);
> > 
> > +	/*
> > +	 * The number of managed pages has changed due to the initialisation
> > +	 * so the pcpu batch and high limits needs to be updated or the limits
> > +	 * will be artificially small.
> > +	 */
> > +	for_each_populated_zone(zone)
> > +		zone_pcp_update(zone);
> > +
> > 	/*
> > 	 * We initialized the rest of the deferred pages.  Permanently disable
> > 	 * on-demand struct page initialization.
> > -- 
> > 2.16.4
> > 
> > 
> 
> Warnings from linux-next,
> 
> [   14.265911][  T659] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
> [   14.265992][  T659] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 659, name: pgdatinit8
> [   14.266044][  T659] 1 lock held by pgdatinit8/659:
> [   14.266075][  T659]  #0: c000201ffca87b40 (&(&pgdat->node_size_lock)->rlock){....}, at: deferred_init_memmap+0xc4/0x26c

This is really surprising to say the least. I do not see any spinlock
held here. Besides that we do sleep in wait_for_completion already.
Is it possible that the patch has been misplaced? zone_pcp_update is
called from page_alloc_init_late which is a different context than
deferred_init_memmap which runs in a separate kthread.

> [   14.266160][  T659] irq event stamp: 26
> [   14.266194][  T659] hardirqs last  enabled at (25): [<c000000000950584>] _raw_spin_unlock_irq+0x44/0x80
> [   14.266246][  T659] hardirqs last disabled at (26): [<c0000000009502ec>] _raw_spin_lock_irqsave+0x3c/0xa0
> [   14.266299][  T659] softirqs last  enabled at (0): [<c0000000000ff8d0>] copy_process+0x720/0x19b0
> [   14.266339][  T659] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [   14.266400][  T659] CPU: 64 PID: 659 Comm: pgdatinit8 Not tainted 5.4.0-rc4-next-20191021 #1
> [   14.266462][  T659] Call Trace:
> [   14.266494][  T659] [c00000003d8efae0] [c000000000921cf4] dump_stack+0xe8/0x164 (unreliable)
> [   14.266538][  T659] [c00000003d8efb30] [c000000000157c54] ___might_sleep+0x334/0x370
> [   14.266577][  T659] [c00000003d8efbb0] [c00000000094a784] __mutex_lock+0x84/0xb20
> [   14.266627][  T659] [c00000003d8efcc0] [c000000000954038] zone_pcp_update+0x34/0x64
> [   14.266677][  T659] [c00000003d8efcf0] [c000000000b9e6bc] deferred_init_memmap+0x1b8/0x26c
> [   14.266740][  T659] [c00000003d8efdb0] [c000000000149528] kthread+0x1a8/0x1b0
> [   14.266792][  T659] [c00000003d8efe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74
> [   14.268288][  T659] node 8 initialised, 1879186 pages in 12200ms
> [   14.268527][  T659] pgdatinit8 (659) used greatest stack depth: 27984 bytes left
> [   15.589983][  T658] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
> [   15.590041][  T658] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 658, name: pgdatinit0
> [   15.590078][  T658] 1 lock held by pgdatinit0/658:
> [   15.590108][  T658]  #0: c000001fff5c7b40 (&(&pgdat->node_size_lock)->rlock){....}, at: deferred_init_memmap+0xc4/0x26c
> [   15.590192][  T658] irq event stamp: 18
> [   15.590224][  T658] hardirqs last  enabled at (17): [<c000000000950654>] _raw_spin_unlock_irqrestore+0x94/0xd0
> [   15.590283][  T658] hardirqs last disabled at (18): [<c0000000009502ec>] _raw_spin_lock_irqsave+0x3c/0xa0
> [   15.590332][  T658] softirqs last  enabled at (0): [<c0000000000ff8d0>] copy_process+0x720/0x19b0
> [   15.590379][  T658] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [   15.590414][  T658] CPU: 8 PID: 658 Comm: pgdatinit0 Tainted: G        W         5.4.0-rc4-next-20191021 #1
> [   15.590460][  T658] Call Trace:
> [   15.590491][  T658] [c00000003d8cfae0] [c000000000921cf4] dump_stack+0xe8/0x164 (unreliable)
> [   15.590541][  T658] [c00000003d8cfb30] [c000000000157c54] ___might_sleep+0x334/0x370
> [   15.590588][  T658] [c00000003d8cfbb0] [c00000000094a784] __mutex_lock+0x84/0xb20
> [   15.590643][  T658] [c00000003d8cfcc0] [c000000000954038] zone_pcp_update+0x34/0x64
> [   15.590689][  T658] [c00000003d8cfcf0] [c000000000b9e6bc] deferred_init_memmap+0x1b8/0x26c
> [   15.590739][  T658] [c00000003d8cfdb0] [c000000000149528] kthread+0x1a8/0x1b0
> [   15.590790][  T658] [c00000003d8cfe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74
Mel Gorman Oct. 21, 2019, 2:25 p.m. UTC | #5
On Mon, Oct 21, 2019 at 10:01:24AM -0400, Qian Cai wrote:
> Warnings from linux-next,
> 
> [   14.265911][  T659] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935
> [   14.265992][  T659] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 659, name: pgdatinit8
> [   14.266044][  T659] 1 lock held by pgdatinit8/659:

Fixed in v2 posted this morning. It should hit linux-next eventually.

Patch
diff mbox series

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c0b2e0306720..f972076d0f6b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1947,6 +1947,14 @@  void __init page_alloc_init_late(void)
 	/* Block until all are initialised */
 	wait_for_completion(&pgdat_init_all_done_comp);
 
+	/*
+	 * The number of managed pages has changed due to the initialisation
+	 * so the pcpu batch and high limits needs to be updated or the limits
+	 * will be artificially small.
+	 */
+	for_each_populated_zone(zone)
+		zone_pcp_update(zone);
+
 	/*
 	 * We initialized the rest of the deferred pages.  Permanently disable
 	 * on-demand struct page initialization.