Greeting,
FYI, we noticed the following commit (built with gcc-9):
commit: 5478fcd0f48322e04ae6c173ad3a1959e066dc83 ("net: embed nr_ids in the xps maps")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
in testcase: ltp
version: ltp-x86_64-14c1f76-1_20210319
with following parameters:
disk: 1HDD
fs: xfs
test: fs-02
ucode: 0xde
test-description: The LTP testsuite contains a collection of tools for testing the Linux kernel and related features.
test-url: http://linux-test-project.github.io/
on test machine: 8 threads Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz with 32G memory
caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
If you fix the issue, kindly add following tag
Reported-by: kernel test robot <[email protected]>
[ 253.104647] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:196
[ 253.113269] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9371, name: read_all
[ 253.121296] CPU: 1 PID: 9371 Comm: read_all Tainted: G I 5.12.0-rc2-00796-g5478fcd0f483 #1
[ 253.130887] Hardware name: Dell Inc. OptiPlex 7050/062KRH, BIOS 1.2.0 12/22/2016
[ 253.138288] Call Trace:
[ 253.140734] dump_stack (kbuild/src/consumer/lib/dump_stack.c:122)
[ 253.144055] ___might_sleep.cold (kbuild/src/consumer/kernel/sched/core.c:8331 kbuild/src/consumer/kernel/sched/core.c:8288)
[ 253.148161] __kmalloc (kbuild/src/consumer/include/linux/sched/mm.h:196 kbuild/src/consumer/mm/slab.h:497 kbuild/src/consumer/mm/slub.c:2826 kbuild/src/consumer/mm/slub.c:2915 kbuild/src/consumer/mm/slub.c:4051)
[ 253.151568] ? xps_rxqs_show (kbuild/src/consumer/net/core/net-sysfs.c:1498 (discriminator 2))
[ 253.155498] xps_rxqs_show (kbuild/src/consumer/net/core/net-sysfs.c:1498 (discriminator 2))
[ 253.159255] sysfs_kf_seq_show (kbuild/src/consumer/fs/sysfs/file.c:62)
[ 253.163273] seq_read_iter (kbuild/src/consumer/fs/seq_file.c:227)
[ 253.167030] new_sync_read (kbuild/src/consumer/fs/read_write.c:416 (discriminator 1))
[ 253.170787] vfs_read (kbuild/src/consumer/fs/read_write.c:496)
[ 253.174105] ksys_read (kbuild/src/consumer/fs/read_write.c:634)
[ 253.177334] do_syscall_64 (kbuild/src/consumer/arch/x86/entry/common.c:46)
[ 253.180923] entry_SYSCALL_64_after_hwframe (kbuild/src/consumer/arch/x86/entry/entry_64.S:112)
[ 253.185978] RIP: 0033:0x7fa906c7c50e
[ 253.189555] Code: 48 8b 15 cd aa 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b6 0f 1f 80 00 00 00 00 8b 05 3a ef 00 00 85 c0 75 16 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 41 54 49 89
All code
========
0: 48 8b 15 cd aa 00 00 mov 0xaacd(%rip),%rdx # 0xaad4
7: f7 d8 neg %eax
9: 64 89 02 mov %eax,%fs:(%rdx)
c: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
13: eb b6 jmp 0xffffffffffffffcb
15: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
1c: 8b 05 3a ef 00 00 mov 0xef3a(%rip),%eax # 0xef5c
22: 85 c0 test %eax,%eax
24: 75 16 jne 0x3c
26: 31 c0 xor %eax,%eax
28: 0f 05 syscall
2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
30: 77 5a ja 0x8c
32: c3 retq
33: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
3a: 00 00
3c: 41 54 push %r12
3e: 49 rex.WB
3f: 89 .byte 0x89
Code starting with the faulting instruction
===========================================
0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
6: 77 5a ja 0x62
8: c3 retq
9: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
10: 00 00
12: 41 54 push %r12
14: 49 rex.WB
15: 89 .byte 0x89
[ 253.208339] RSP: 002b:00007ffcb9e87038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[ 253.215926] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa906c7c50e
[ 253.223064] RDX: 00000000000003ff RSI: 00007ffcb9e874f0 RDI: 0000000000000004
[ 253.230203] RBP: 00007fa906a9d000 R08: 0000000000000020 R09: 0000000000000000
[ 253.237342] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcb9e870f0
[ 253.244481] R13: 0000000046178f11 R14: 00007ffcb9e870f1 R15: 00007ffcb9e874f0
[ 253.311298] WARNING! power/level is deprecated; use power/control instead
[ 253.391095] bdi 8:16: the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.
[ 253.461822] LTP: starting fs_racer (fs_racer.sh -t 5)
[ 253.462425] read_all.c:446: TPASS: Finished reading files
[ 253.467003]
[ 253.474072]
[ 253.474074]
[ 253.477410] Summary:
[ 253.477413]
[ 253.484390] passed 1
[ 253.484394]
[ 253.489272] failed 0
[ 253.489275]
[ 253.494226] broken 0
[ 253.494229]
[ 253.498785] skipped 0
[ 253.498787]
[ 253.503077] warnings 0
[ 253.503079]
[ 253.507819] <<<execution_status>>>
[ 253.507822]
[ 253.513662] initiation_status="ok"
[ 253.513665]
[ 253.520191] duration=2 termination_type=exited termination_id=0 corefile=no
[ 253.520195]
[ 253.529408] cutime=31 cstime=146
[ 253.529411]
[ 253.534670] <<<test_end>>>
[ 253.534673]
[ 253.539491] <<<test_start>>>
[ 253.539493]
[ 253.544909] tag=fs_racer stime=1616256119
[ 253.544912]
[ 253.551150] cmdline="fs_racer.sh -t 5"
[ 253.551153]
[ 253.556903] contacts=""
[ 253.556906]
[ 253.561450] analysis=exit
[ 253.561453]
[ 253.566269] <<<test_output>>>
[ 253.566272]
[ 253.571088] 1052827
[ 253.571091]
[ 253.574964] 28626
[ 253.574967]
[ 253.578713] 1968932
[ 253.578715]
[ 253.582631] 1266945
[ 253.582634]
[ 253.586490] 560991
[ 253.586492]
[ 253.590260] 624408
[ 253.590263]
[ 253.594108] 1824335
[ 253.594111]
[ 253.597994] 544694
[ 253.597996]
[ 253.601834] 1480574
[ 253.601837]
[ 255.471244] 1313272
[ 255.471248]
[ 255.475221] 86184
[ 255.475224]
[ 255.479101] 1728568
[ 255.479104]
[ 255.483123] 226081
[ 255.483126]
[ 255.500155] 1048554
[ 255.500160]
[ 255.504223] 1268410
[ 255.504225]
[ 255.508281] 1717154
[ 255.508284]
[ 255.512349] 1306802
[ 255.512352]
[ 255.516330] 440748
[ 255.516333]
[ 255.520196] 79348
[ 255.520200]
[ 255.524114] 1129184
[ 255.524118]
[ 255.528199] 1587817
[ 255.528202]
[ 255.532269] 1389507
[ 255.532272]
[ 255.536349] 1027069
[ 255.536352]
[ 255.540361] 1513046
[ 255.540364]
[ 255.544272] 449232
[ 255.544275]
[ 255.866251] 83254
[ 255.866255]
[ 255.870121] 1198889
To reproduce:
git clone https://github.com/intel/lkp-tests.git
cd lkp-tests
bin/lkp install job.yaml # job file is attached in this email
bin/lkp split-job --compatible job.yaml
bin/lkp run compatible-job.yaml
---
0DAY/LKP+ Test Infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation
Thanks,
Oliver Sang
I only had a quick look at this, but I think the issue should be fixed
with:
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e16d54aabd4c..3ae3c20eb64c 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1378,7 +1378,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
nr_ids = dev_maps ? dev_maps->nr_ids :
(type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
- mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
+ mask = bitmap_zalloc(nr_ids, GFP_ATOMIC);
if (!mask) {
rcu_read_unlock();
return -ENOMEM;
I'll run some tests and send a fix.
Antoine
Quoting kernel test robot (2021-03-22 09:35:53)
>
> FYI, we noticed the following commit (built with gcc-9):
>
> commit: 5478fcd0f48322e04ae6c173ad3a1959e066dc83 ("net: embed nr_ids in the xps maps")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
>
> in testcase: ltp
> version: ltp-x86_64-14c1f76-1_20210319
> with following parameters:
>
> disk: 1HDD
> fs: xfs
> test: fs-02
> ucode: 0xde
>
> test-description: The LTP testsuite contains a collection of tools for testing the Linux kernel and related features.
> test-url: http://linux-test-project.github.io/
>
>
> on test machine: 8 threads Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz with 32G memory
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <[email protected]>
>
>
> [ 253.104647] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:196
> [ 253.113269] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 9371, name: read_all
> [ 253.121296] CPU: 1 PID: 9371 Comm: read_all Tainted: G I 5.12.0-rc2-00796-g5478fcd0f483 #1
> [ 253.130887] Hardware name: Dell Inc. OptiPlex 7050/062KRH, BIOS 1.2.0 12/22/2016
> [ 253.138288] Call Trace:
> [ 253.140734] dump_stack (kbuild/src/consumer/lib/dump_stack.c:122)
> [ 253.144055] ___might_sleep.cold (kbuild/src/consumer/kernel/sched/core.c:8331 kbuild/src/consumer/kernel/sched/core.c:8288)
> [ 253.148161] __kmalloc (kbuild/src/consumer/include/linux/sched/mm.h:196 kbuild/src/consumer/mm/slab.h:497 kbuild/src/consumer/mm/slub.c:2826 kbuild/src/consumer/mm/slub.c:2915 kbuild/src/consumer/mm/slub.c:4051)
> [ 253.151568] ? xps_rxqs_show (kbuild/src/consumer/net/core/net-sysfs.c:1498 (discriminator 2))
> [ 253.155498] xps_rxqs_show (kbuild/src/consumer/net/core/net-sysfs.c:1498 (discriminator 2))
> [ 253.159255] sysfs_kf_seq_show (kbuild/src/consumer/fs/sysfs/file.c:62)
> [ 253.163273] seq_read_iter (kbuild/src/consumer/fs/seq_file.c:227)
> [ 253.167030] new_sync_read (kbuild/src/consumer/fs/read_write.c:416 (discriminator 1))
> [ 253.170787] vfs_read (kbuild/src/consumer/fs/read_write.c:496)
> [ 253.174105] ksys_read (kbuild/src/consumer/fs/read_write.c:634)
> [ 253.177334] do_syscall_64 (kbuild/src/consumer/arch/x86/entry/common.c:46)
> [ 253.180923] entry_SYSCALL_64_after_hwframe (kbuild/src/consumer/arch/x86/entry/entry_64.S:112)
> [ 253.185978] RIP: 0033:0x7fa906c7c50e
> [ 253.189555] Code: 48 8b 15 cd aa 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b6 0f 1f 80 00 00 00 00 8b 05 3a ef 00 00 85 c0 75 16 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 41 54 49 89
> All code
> ========
> 0: 48 8b 15 cd aa 00 00 mov 0xaacd(%rip),%rdx # 0xaad4
> 7: f7 d8 neg %eax
> 9: 64 89 02 mov %eax,%fs:(%rdx)
> c: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
> 13: eb b6 jmp 0xffffffffffffffcb
> 15: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
> 1c: 8b 05 3a ef 00 00 mov 0xef3a(%rip),%eax # 0xef5c
> 22: 85 c0 test %eax,%eax
> 24: 75 16 jne 0x3c
> 26: 31 c0 xor %eax,%eax
> 28: 0f 05 syscall
> 2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
> 30: 77 5a ja 0x8c
> 32: c3 retq
> 33: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
> 3a: 00 00
> 3c: 41 54 push %r12
> 3e: 49 rex.WB
> 3f: 89 .byte 0x89
>
> Code starting with the faulting instruction
> ===========================================
> 0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
> 6: 77 5a ja 0x62
> 8: c3 retq
> 9: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
> 10: 00 00
> 12: 41 54 push %r12
> 14: 49 rex.WB
> 15: 89 .byte 0x89
> [ 253.208339] RSP: 002b:00007ffcb9e87038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [ 253.215926] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa906c7c50e
> [ 253.223064] RDX: 00000000000003ff RSI: 00007ffcb9e874f0 RDI: 0000000000000004
> [ 253.230203] RBP: 00007fa906a9d000 R08: 0000000000000020 R09: 0000000000000000
> [ 253.237342] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcb9e870f0
> [ 253.244481] R13: 0000000046178f11 R14: 00007ffcb9e870f1 R15: 00007ffcb9e874f0
> [ 253.311298] WARNING! power/level is deprecated; use power/control instead
> [ 253.391095] bdi 8:16: the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.
> [ 253.461822] LTP: starting fs_racer (fs_racer.sh -t 5)
> [ 253.462425] read_all.c:446: TPASS: Finished reading files
> [ 253.467003]
> [ 253.474072]
> [ 253.474074]
> [ 253.477410] Summary:
> [ 253.477413]
> [ 253.484390] passed 1
> [ 253.484394]
> [ 253.489272] failed 0
> [ 253.489275]
> [ 253.494226] broken 0
> [ 253.494229]
> [ 253.498785] skipped 0
> [ 253.498787]
> [ 253.503077] warnings 0
> [ 253.503079]
> [ 253.507819] <<<execution_status>>>
> [ 253.507822]
> [ 253.513662] initiation_status="ok"
> [ 253.513665]
> [ 253.520191] duration=2 termination_type=exited termination_id=0 corefile=no
> [ 253.520195]
> [ 253.529408] cutime=31 cstime=146
> [ 253.529411]
> [ 253.534670] <<<test_end>>>
> [ 253.534673]
> [ 253.539491] <<<test_start>>>
> [ 253.539493]
> [ 253.544909] tag=fs_racer stime=1616256119
> [ 253.544912]
> [ 253.551150] cmdline="fs_racer.sh -t 5"
> [ 253.551153]
> [ 253.556903] contacts=""
> [ 253.556906]
> [ 253.561450] analysis=exit
> [ 253.561453]
> [ 253.566269] <<<test_output>>>
> [ 253.566272]
> [ 253.571088] 1052827
> [ 253.571091]
> [ 253.574964] 28626
> [ 253.574967]
> [ 253.578713] 1968932
> [ 253.578715]
> [ 253.582631] 1266945
> [ 253.582634]
> [ 253.586490] 560991
> [ 253.586492]
> [ 253.590260] 624408
> [ 253.590263]
> [ 253.594108] 1824335
> [ 253.594111]
> [ 253.597994] 544694
> [ 253.597996]
> [ 253.601834] 1480574
> [ 253.601837]
> [ 255.471244] 1313272
> [ 255.471248]
> [ 255.475221] 86184
> [ 255.475224]
> [ 255.479101] 1728568
> [ 255.479104]
> [ 255.483123] 226081
> [ 255.483126]
> [ 255.500155] 1048554
> [ 255.500160]
> [ 255.504223] 1268410
> [ 255.504225]
> [ 255.508281] 1717154
> [ 255.508284]
> [ 255.512349] 1306802
> [ 255.512352]
> [ 255.516330] 440748
> [ 255.516333]
> [ 255.520196] 79348
> [ 255.520200]
> [ 255.524114] 1129184
> [ 255.524118]
> [ 255.528199] 1587817
> [ 255.528202]
> [ 255.532269] 1389507
> [ 255.532272]
> [ 255.536349] 1027069
> [ 255.536352]
> [ 255.540361] 1513046
> [ 255.540364]
> [ 255.544272] 449232
> [ 255.544275]
> [ 255.866251] 83254
> [ 255.866255]
> [ 255.870121] 1198889
>
>
> To reproduce:
>
> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp install job.yaml # job file is attached in this email
> bin/lkp split-job --compatible job.yaml
> bin/lkp run compatible-job.yaml
>
>
>
> ---
> 0DAY/LKP+ Test Infrastructure Open Source Technology Center
> https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation
>
> Thanks,
> Oliver Sang
>
On Mon, Mar 22, 2021 at 09:55:50AM +0100, Antoine Tenart wrote:
> I only had a quick look at this, but I think the issue should be fixed
> with:
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index e16d54aabd4c..3ae3c20eb64c 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1378,7 +1378,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
> nr_ids = dev_maps ? dev_maps->nr_ids :
> (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
>
> - mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> + mask = bitmap_zalloc(nr_ids, GFP_ATOMIC);
> if (!mask) {
> rcu_read_unlock();
> return -ENOMEM;
sysfs isn't a good reason to use GFP_ATOMIC.
try something like this:
- mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
+ mask = bitmap_zalloc(nr_ids, GFP_NOWAIT);
if (!mask) {
+ int new_nr_ids;
+
rcu_read_unlock();
- return -ENOMEM;
+ mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
+ if (!mask)
+ return -ENOMEM;
+ rcu_read_lock();
+ dev_maps = rcu_dereference(dev->xps_maps[type]);
+ /* if nr_ids shrank while we slept, do not overrun array.
+ * if it increased, we just won't show the new ones
+ */
+ new_nr_ids = dev_maps ? dev_maps->nr_ids :
+ (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
+ if (new_nr_ids < nr_ids)
+ nr_ids = new_nr_ids;
Quoting Matthew Wilcox (2021-03-22 10:05:36)
> On Mon, Mar 22, 2021 at 09:55:50AM +0100, Antoine Tenart wrote:
> > I only had a quick look at this, but I think the issue should be fixed
> > with:
> >
> > diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> > index e16d54aabd4c..3ae3c20eb64c 100644
> > --- a/net/core/net-sysfs.c
> > +++ b/net/core/net-sysfs.c
> > @@ -1378,7 +1378,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
> > nr_ids = dev_maps ? dev_maps->nr_ids :
> > (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
> >
> > - mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> > + mask = bitmap_zalloc(nr_ids, GFP_ATOMIC);
> > if (!mask) {
> > rcu_read_unlock();
> > return -ENOMEM;
>
> sysfs isn't a good reason to use GFP_ATOMIC.
>
> try something like this:
>
> - mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> + mask = bitmap_zalloc(nr_ids, GFP_NOWAIT);
> if (!mask) {
> + int new_nr_ids;
> +
> rcu_read_unlock();
> - return -ENOMEM;
> + mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> + if (!mask)
> + return -ENOMEM;
> + rcu_read_lock();
> + dev_maps = rcu_dereference(dev->xps_maps[type]);
> + /* if nr_ids shrank while we slept, do not overrun array.
> + * if it increased, we just won't show the new ones
> + */
> + new_nr_ids = dev_maps ? dev_maps->nr_ids :
> + (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
> + if (new_nr_ids < nr_ids)
> + nr_ids = new_nr_ids;
Thanks for the suggestion, I'll look into that. We could also just
return -ENOMEM if the first allocation fails, retrying adds a lot of
complexity.
Antoine
On Mon, Mar 22, 2021 at 2:26 AM Antoine Tenart <[email protected]> wrote:
>
> Quoting Matthew Wilcox (2021-03-22 10:05:36)
> > On Mon, Mar 22, 2021 at 09:55:50AM +0100, Antoine Tenart wrote:
> > > I only had a quick look at this, but I think the issue should be fixed
> > > with:
> > >
> > > diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> > > index e16d54aabd4c..3ae3c20eb64c 100644
> > > --- a/net/core/net-sysfs.c
> > > +++ b/net/core/net-sysfs.c
> > > @@ -1378,7 +1378,7 @@ static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
> > > nr_ids = dev_maps ? dev_maps->nr_ids :
> > > (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
> > >
> > > - mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> > > + mask = bitmap_zalloc(nr_ids, GFP_ATOMIC);
> > > if (!mask) {
> > > rcu_read_unlock();
> > > return -ENOMEM;
> >
> > sysfs isn't a good reason to use GFP_ATOMIC.
> >
> > try something like this:
> >
> > - mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> > + mask = bitmap_zalloc(nr_ids, GFP_NOWAIT);
> > if (!mask) {
> > + int new_nr_ids;
> > +
> > rcu_read_unlock();
> > - return -ENOMEM;
> > + mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> > + if (!mask)
> > + return -ENOMEM;
> > + rcu_read_lock();
> > + dev_maps = rcu_dereference(dev->xps_maps[type]);
> > + /* if nr_ids shrank while we slept, do not overrun array.
> > + * if it increased, we just won't show the new ones
> > + */
> > + new_nr_ids = dev_maps ? dev_maps->nr_ids :
> > + (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
> > + if (new_nr_ids < nr_ids)
> > + nr_ids = new_nr_ids;
>
> Thanks for the suggestion, I'll look into that. We could also just
> return -ENOMEM if the first allocation fails, retrying adds a lot of
> complexity.
>
> Antoine
I agree that the retry logic is probably unneeded. In addition we
probably don't need GFP_ATOMIC as GFP_NOWAIT will probably be good
enough as the allocation can fail and just return an -ENOMEM in the
case of low memory.
Thanks.
- Alex