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| Started by | Abdul Haleem <abdhalee@linux.vnet.ibm.com> |
|---|---|
| First post | 2017-08-19 12:30 +0200 |
| Last post | 2017-08-21 14:00 +0200 |
| Articles | 4 — 3 participants |
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[linux-next][bisected c64e09ce] sysctl command hung indefinitely Abdul Haleem <abdhalee@linux.vnet.ibm.com> - 2017-08-19 12:30 +0200
Re: [linux-next][bisected c64e09ce] sysctl command hung indefinitely Michal Hocko <mhocko@kernel.org> - 2017-08-21 10:00 +0200
Re: [linux-next][bisected c64e09ce] sysctl command hung indefinitely Abdul Haleem <abdhalee@linux.vnet.ibm.com> - 2017-08-21 10:50 +0200
Re: [linux-next][bisected c64e09ce] sysctl command hung indefinitely Stephen Rothwell <sfr@canb.auug.org.au> - 2017-08-21 14:00 +0200
| From | Abdul Haleem <abdhalee@linux.vnet.ibm.com> |
|---|---|
| Date | 2017-08-19 12:30 +0200 |
| Subject | [linux-next][bisected c64e09ce] sysctl command hung indefinitely |
| Message-ID | <ug9aW-77-11@gated-at.bofh.it> |
Hi Michal,
'sysctl -a' command never completes on my PowerPC machine with latest
next kernel (As of next-20170811)
Machine Type : Power8 bare-metal
Kernel version : 4.13.0-rc4-next-20170817
gcc version : 4.8.5
command output
--------------
$ sysctl -a
[...
vm.hugetlb_shm_group = 0
vm.laptop_mode = 0
vm.legacy_va_layout = 0
vm.lowmem_reserve_ratio = 256 256 32
vm.max_map_count = 65530
vm.min_free_kbytes = 6637
vm.min_slab_ratio = 5
vm.min_unmapped_ratio = 1
vm.mmap_min_addr = 4096
vm.mmap_rnd_bits = 14
vm.mmap_rnd_compat_bits = 7
vm.nr_hugepages = 0
vm.nr_hugepages_mempolicy = 0
vm.nr_overcommit_hugepages = 0
vm.nr_pdflush_threads = 0
vm.numa_zonelist_order = Node
vm.numa_zonelist_order = e
vm.numa_zonelist_order = ode
vm.numa_zonelist_order =
vm.numa_zonelist_order = de
vm.numa_zonelist_order = Node
vm.numa_zonelist_order = e
vm.numa_zonelist_order = ode
vm.numa_zonelist_order =
vm.numa_zonelist_order = de
vm.numa_zonelist_order = Node
vm.numa_zonelist_order = e
vm.numa_zonelist_order = ode
vm.numa_zonelist_order =
vm.numa_zonelist_order = de
vm.numa_zonelist_order = Node
vm.numa_zonelist_order = e
vm.numa_zonelist_order = ode
....]
The last string 'vm.numa_zonelist_order = ' keeps flooding the stdout
and command never exit.
A bisection resulted commit c64e09ce mm, page_alloc: rip out
ZONELIST_ORDER_ZONE
Command exits cleanly when the above commit is reverted.
from the commit I see some changes to kernel/sysctl.c
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6648fbb..0d51ec1 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1574,8 +1574,6 @@ static int sysrq_sysctl_handler(struct ctl_table
*table, int write,
#ifdef CONFIG_NUMA
{
.procname = "numa_zonelist_order",
- .data = &numa_zonelist_order,
- .maxlen = NUMA_ZONELIST_ORDER_LEN,
.mode = 0644,
.proc_handler = numa_zonelist_order_handler,
},
does the above change has caused the noise ?
--
Regard's
Abdul Haleem
IBM Linux Technology Centre
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| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Date | 2017-08-21 10:00 +0200 |
| Message-ID | <ugPMR-1su-7@gated-at.bofh.it> |
| In reply to | #1715625 |
On Sat 19-08-17 15:49:31, Abdul Haleem wrote:
> Hi Michal,
>
> 'sysctl -a' command never completes on my PowerPC machine with latest
> next kernel (As of next-20170811)
>
> Machine Type : Power8 bare-metal
> Kernel version : 4.13.0-rc4-next-20170817
> gcc version : 4.8.5
>
>
> command output
> --------------
> $ sysctl -a
> [...
> vm.hugetlb_shm_group = 0
> vm.laptop_mode = 0
> vm.legacy_va_layout = 0
> vm.lowmem_reserve_ratio = 256 256 32
> vm.max_map_count = 65530
> vm.min_free_kbytes = 6637
> vm.min_slab_ratio = 5
> vm.min_unmapped_ratio = 1
> vm.mmap_min_addr = 4096
> vm.mmap_rnd_bits = 14
> vm.mmap_rnd_compat_bits = 7
> vm.nr_hugepages = 0
> vm.nr_hugepages_mempolicy = 0
> vm.nr_overcommit_hugepages = 0
> vm.nr_pdflush_threads = 0
> vm.numa_zonelist_order = Node
> vm.numa_zonelist_order = e
> vm.numa_zonelist_order = ode
> vm.numa_zonelist_order =
> vm.numa_zonelist_order = de
> vm.numa_zonelist_order = Node
> vm.numa_zonelist_order = e
> vm.numa_zonelist_order = ode
> vm.numa_zonelist_order =
> vm.numa_zonelist_order = de
> vm.numa_zonelist_order = Node
> vm.numa_zonelist_order = e
> vm.numa_zonelist_order = ode
> vm.numa_zonelist_order =
> vm.numa_zonelist_order = de
> vm.numa_zonelist_order = Node
> vm.numa_zonelist_order = e
> vm.numa_zonelist_order = ode
> ....]
>
> The last string 'vm.numa_zonelist_order = ' keeps flooding the stdout
> and command never exit.
>
> A bisection resulted commit c64e09ce mm, page_alloc: rip out
> ZONELIST_ORDER_ZONE
Yeah, my read implementation is broken. I do not update the ppos and so
the reader doesn't know it should exit. Mel was suggesting to keep the
proc_dostring but I thought I was more clever. Sigh...
This should do the trick. Andrew, could you fold it into
mm-page_alloc-rip-out-zonelist_order_zone.patch please?
Thanks for the report Abdul!
---
commit 69885605ee3ba681deb54021e3df645f46589ba1
Author: Michal Hocko <mhocko@suse.com>
Date: Mon Aug 21 09:46:04 2017 +0200
mmotm: mm-page_alloc-rip-out-zonelist_order_zone-fix
Abdul has noticed that reading sysctl vm.numa_zonelist_order
read will never terminate. This is because of
http://lkml.kernel.org/r/20170714080006.7250-2-mhocko@kernel.org
where the reading side doesn't update ppos and so the reader will
never get 0. Return back to proc_dostring which does all the necessary
stuff.
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fda9afbd14d9..e7e92c8f4883 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -894,6 +894,8 @@ int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *, int,
extern int numa_zonelist_order_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
+extern char numa_zonelist_order[];
+#define NUMA_ZONELIST_ORDER_LEN 16
#ifndef CONFIG_NEED_MULTIPLE_NODES
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0cbce40f5426..655686d546cb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1553,6 +1553,8 @@ static struct ctl_table vm_table[] = {
#ifdef CONFIG_NUMA
{
.procname = "numa_zonelist_order",
+ .data = &numa_zonelist_order,
+ .maxlen = NUMA_ZONELIST_ORDER_LEN,
.mode = 0644,
.proc_handler = numa_zonelist_order_handler,
},
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5cba36337893..b55e97decac4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4859,6 +4859,8 @@ static __init int setup_numa_zonelist_order(char *s)
}
early_param("numa_zonelist_order", setup_numa_zonelist_order);
+char numa_zonelist_order[] = "Node";
+
/*
* sysctl handler for numa_zonelist_order
*/
@@ -4869,12 +4871,8 @@ int numa_zonelist_order_handler(struct ctl_table *table, int write,
char *str;
int ret;
- if (!write) {
- int len = sizeof("Node");
- if (copy_to_user(buffer, "Node", len))
- return -EFAULT;
- return len;
- }
+ if (!write)
+ return proc_dostring(table, write, buffer, length, ppos);
str = memdup_user_nul(buffer, 16);
if (IS_ERR(str))
return PTR_ERR(str);
--
Michal Hocko
SUSE Labs
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| From | Abdul Haleem <abdhalee@linux.vnet.ibm.com> |
|---|---|
| Date | 2017-08-21 10:50 +0200 |
| Message-ID | <ugQzf-20E-1@gated-at.bofh.it> |
| In reply to | #1716149 |
On Mon, 2017-08-21 at 09:50 +0200, Michal Hocko wrote: > On Sat 19-08-17 15:49:31, Abdul Haleem wrote: > > Hi Michal, > > > > 'sysctl -a' command never completes on my PowerPC machine with latest > > next kernel (As of next-20170811) > > > > Machine Type : Power8 bare-metal > > Kernel version : 4.13.0-rc4-next-20170817 > > gcc version : 4.8.5 > > > > > > command output > > -------------- > > $ sysctl -a > > [... > > vm.hugetlb_shm_group = 0 > > vm.laptop_mode = 0 > > vm.legacy_va_layout = 0 > > vm.lowmem_reserve_ratio = 256 256 32 > > vm.max_map_count = 65530 > > vm.min_free_kbytes = 6637 > > vm.min_slab_ratio = 5 > > vm.min_unmapped_ratio = 1 > > vm.mmap_min_addr = 4096 > > vm.mmap_rnd_bits = 14 > > vm.mmap_rnd_compat_bits = 7 > > vm.nr_hugepages = 0 > > vm.nr_hugepages_mempolicy = 0 > > vm.nr_overcommit_hugepages = 0 > > vm.nr_pdflush_threads = 0 > > vm.numa_zonelist_order = Node > > vm.numa_zonelist_order = e > > vm.numa_zonelist_order = ode > > vm.numa_zonelist_order = > > vm.numa_zonelist_order = de > > vm.numa_zonelist_order = Node > > vm.numa_zonelist_order = e > > vm.numa_zonelist_order = ode > > vm.numa_zonelist_order = > > vm.numa_zonelist_order = de > > vm.numa_zonelist_order = Node > > vm.numa_zonelist_order = e > > vm.numa_zonelist_order = ode > > vm.numa_zonelist_order = > > vm.numa_zonelist_order = de > > vm.numa_zonelist_order = Node > > vm.numa_zonelist_order = e > > vm.numa_zonelist_order = ode > > ....] > > > > The last string 'vm.numa_zonelist_order = ' keeps flooding the stdout > > and command never exit. > > > > A bisection resulted commit c64e09ce mm, page_alloc: rip out > > ZONELIST_ORDER_ZONE > > Yeah, my read implementation is broken. I do not update the ppos and so > the reader doesn't know it should exit. Mel was suggesting to keep the > proc_dostring but I thought I was more clever. Sigh... > > This should do the trick. Andrew, could you fold it into > mm-page_alloc-rip-out-zonelist_order_zone.patch please? > > Thanks for the report Abdul! > > --- > commit 69885605ee3ba681deb54021e3df645f46589ba1 > Author: Michal Hocko <mhocko@suse.com> > Date: Mon Aug 21 09:46:04 2017 +0200 > > mmotm: mm-page_alloc-rip-out-zonelist_order_zone-fix > > Abdul has noticed that reading sysctl vm.numa_zonelist_order > read will never terminate. This is because of > http://lkml.kernel.org/r/20170714080006.7250-2-mhocko@kernel.org > where the reading side doesn't update ppos and so the reader will > never get 0. Return back to proc_dostring which does all the necessary > stuff. > > Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> > Signed-off-by: Michal Hocko <mhocko@suse.com> > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index fda9afbd14d9..e7e92c8f4883 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h Thanks for the fix Michal, the patch fixes the problem. Reported-and-Tested-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> -- Regard's Abdul Haleem IBM Linux Technology Centre
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| From | Stephen Rothwell <sfr@canb.auug.org.au> |
|---|---|
| Date | 2017-08-21 14:00 +0200 |
| Subject | Re: [linux-next][bisected c64e09ce] sysctl command hung indefinitely |
| Message-ID | <ugTx8-3UE-19@gated-at.bofh.it> |
| In reply to | #1716149 |
Hi Michal, On Mon, 21 Aug 2017 09:50:01 +0200 Michal Hocko <mhocko@kernel.org> wrote: > > commit 69885605ee3ba681deb54021e3df645f46589ba1 > Author: Michal Hocko <mhocko@suse.com> > Date: Mon Aug 21 09:46:04 2017 +0200 > > mmotm: mm-page_alloc-rip-out-zonelist_order_zone-fix > > Abdul has noticed that reading sysctl vm.numa_zonelist_order > read will never terminate. This is because of > http://lkml.kernel.org/r/20170714080006.7250-2-mhocko@kernel.org > where the reading side doesn't update ppos and so the reader will > never get 0. Return back to proc_dostring which does all the necessary > stuff. > > Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> > Signed-off-by: Michal Hocko <mhocko@suse.com> I have added that to linux-next for tomorrow. -- Cheers, Stephen Rothwell
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