* [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
@ 2022-09-06 16:04 Phil Auld
2022-09-06 17:02 ` Greg Kroah-Hartman
2022-09-06 18:09 ` Yury Norov
0 siblings, 2 replies; 7+ messages in thread
From: Phil Auld @ 2022-09-06 16:04 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, Rafael J . Wysocki, Barry Song, Tian Tao,
Yury Norov, feng xiangjun, stable
As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
This leads to very large file sizes:
topology$ ls -l
total 0
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
-r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
-r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
-r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
-r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
-r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
Adjust the inequality to catch the case when NR_CPUS is configured
to a small value.
Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
Reported-by: feng xiangjun <fengxj325@gmail.com>
Signed-off-by: Phil Auld <pauld@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: stable@vger.kernel.org
Cc: feng xiangjun <fengxj325@gmail.com>
---
include/linux/cpumask.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index bd047864c7ac..7b1349612d6d 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
* cover a worst-case of every other cpu being on one of two nodes for a
* very large NR_CPUS.
*
- * Use PAGE_SIZE as a minimum for smaller configurations.
+ * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
+ * unsigned comparison to -1.
*/
-#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
+#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
#define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
--
2.31.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 16:04 [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES Phil Auld
@ 2022-09-06 17:02 ` Greg Kroah-Hartman
2022-09-06 17:24 ` Phil Auld
2022-09-06 18:09 ` Yury Norov
1 sibling, 1 reply; 7+ messages in thread
From: Greg Kroah-Hartman @ 2022-09-06 17:02 UTC (permalink / raw)
To: Phil Auld
Cc: linux-kernel, Rafael J . Wysocki, Barry Song, Tian Tao,
Yury Norov, feng xiangjun, stable
On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> This leads to very large file sizes:
>
> topology$ ls -l
> total 0
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
Yeah, lots of CPUs! :)
> -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
>
> Adjust the inequality to catch the case when NR_CPUS is configured
> to a small value.
>
> Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> Reported-by: feng xiangjun <fengxj325@gmail.com>
> Signed-off-by: Phil Auld <pauld@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Yury Norov <yury.norov@gmail.com>
> Cc: stable@vger.kernel.org
> Cc: feng xiangjun <fengxj325@gmail.com>
> ---
> include/linux/cpumask.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index bd047864c7ac..7b1349612d6d 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> * cover a worst-case of every other cpu being on one of two nodes for a
> * very large NR_CPUS.
> *
> - * Use PAGE_SIZE as a minimum for smaller configurations.
> + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> + * unsigned comparison to -1.
> */
> -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
> ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
> #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
>
> --
> 2.31.1
>
Nice catch. What type of systems did you run this on to verify it will
work?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 17:02 ` Greg Kroah-Hartman
@ 2022-09-06 17:24 ` Phil Auld
0 siblings, 0 replies; 7+ messages in thread
From: Phil Auld @ 2022-09-06 17:24 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, Rafael J . Wysocki, Barry Song, Tian Tao,
Yury Norov, feng xiangjun, stable
On Tue, Sep 06, 2022 at 07:02:37PM +0200 Greg Kroah-Hartman wrote:
> On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> > As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> > This leads to very large file sizes:
> >
> > topology$ ls -l
> > total 0
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
>
> Yeah, lots of CPUs! :)
>
Yep, apparently things like lscpu fail with this size.
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
> >
> > Adjust the inequality to catch the case when NR_CPUS is configured
> > to a small value.
> >
> > Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> > Reported-by: feng xiangjun <fengxj325@gmail.com>
> > Signed-off-by: Phil Auld <pauld@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Yury Norov <yury.norov@gmail.com>
> > Cc: stable@vger.kernel.org
> > Cc: feng xiangjun <fengxj325@gmail.com>
> > ---
> > include/linux/cpumask.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> > index bd047864c7ac..7b1349612d6d 100644
> > --- a/include/linux/cpumask.h
> > +++ b/include/linux/cpumask.h
> > @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> > * cover a worst-case of every other cpu being on one of two nodes for a
> > * very large NR_CPUS.
> > *
> > - * Use PAGE_SIZE as a minimum for smaller configurations.
> > + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> > + * unsigned comparison to -1.
> > */
> > -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> > +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
> > ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
> > #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
> >
> > --
> > 2.31.1
> >
>
> Nice catch. What type of systems did you run this on to verify it will
> work?
>
Feng ran it on his 2 cpu laptop. I ran it on my usual test bed (80 cpus) but
configured both with NR_CPUS at 8192 and at 2.
It's not really dependent on the actual system. It's a compile time config
option. I failed to set it small when testing the first one.
The fix here is just maths :)
With NR_CPUS == 2:
# ls -l /sys/devices/system/cpu/cpu0/topology/
total 0
-r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_cpus
-r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_cpus_list
-r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_id
-r--r--r--. 1 root root 4096 Sep 6 11:40 core_cpus
-r--r--r--. 1 root root 4096 Sep 6 11:40 core_cpus_list
-r--r--r--. 1 root root 4096 Sep 6 11:40 core_id
-r--r--r--. 1 root root 4096 Sep 6 11:29 core_siblings
-r--r--r--. 1 root root 4096 Sep 6 11:40 core_siblings_list
...
Cheers,
Phil
> thanks,
>
> greg k-h
>
--
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 16:04 [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES Phil Auld
2022-09-06 17:02 ` Greg Kroah-Hartman
@ 2022-09-06 18:09 ` Yury Norov
2022-09-06 18:15 ` Yury Norov
2022-09-06 18:57 ` Phil Auld
1 sibling, 2 replies; 7+ messages in thread
From: Yury Norov @ 2022-09-06 18:09 UTC (permalink / raw)
To: Phil Auld
Cc: linux-kernel, Greg Kroah-Hartman, Rafael J . Wysocki, Barry Song,
Tian Tao, feng xiangjun, stable
On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> This leads to very large file sizes:
>
> topology$ ls -l
> total 0
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
> -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
>
> Adjust the inequality to catch the case when NR_CPUS is configured
> to a small value.
>
> Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> Reported-by: feng xiangjun <fengxj325@gmail.com>
> Signed-off-by: Phil Auld <pauld@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Yury Norov <yury.norov@gmail.com>
> Cc: stable@vger.kernel.org
> Cc: feng xiangjun <fengxj325@gmail.com>
> ---
> include/linux/cpumask.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index bd047864c7ac..7b1349612d6d 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> * cover a worst-case of every other cpu being on one of two nodes for a
> * very large NR_CPUS.
> *
> - * Use PAGE_SIZE as a minimum for smaller configurations.
> + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> + * unsigned comparison to -1.
> */
> -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
Maybe it would be easier to read with less braces and '>=' instead of '>'?
#define CPUMAP_FILE_MAX_BYTES \
(NR_CPUS * 9 / 32 >= PAGE_SIZE ? NR_CPUS * 9 / 32 - 1 : PAGE_SIZE)
Anyways, this is a good catch. If you think it doesn't worth an
update, I can take it in bitmap-for-next as-is.
> ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
> #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
>
> --
> 2.31.1
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 18:09 ` Yury Norov
@ 2022-09-06 18:15 ` Yury Norov
2022-09-06 18:57 ` Phil Auld
1 sibling, 0 replies; 7+ messages in thread
From: Yury Norov @ 2022-09-06 18:15 UTC (permalink / raw)
To: Phil Auld
Cc: linux-kernel, Greg Kroah-Hartman, Rafael J . Wysocki, Barry Song,
Tian Tao, feng xiangjun, stable
On Tue, Sep 06, 2022 at 11:09:54AM -0700, Yury Norov wrote:
> On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> > As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> > This leads to very large file sizes:
> >
> > topology$ ls -l
> > total 0
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
> >
> > Adjust the inequality to catch the case when NR_CPUS is configured
> > to a small value.
> >
> > Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> > Reported-by: feng xiangjun <fengxj325@gmail.com>
> > Signed-off-by: Phil Auld <pauld@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Yury Norov <yury.norov@gmail.com>
> > Cc: stable@vger.kernel.org
> > Cc: feng xiangjun <fengxj325@gmail.com>
> > ---
> > include/linux/cpumask.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> > index bd047864c7ac..7b1349612d6d 100644
> > --- a/include/linux/cpumask.h
> > +++ b/include/linux/cpumask.h
> > @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> > * cover a worst-case of every other cpu being on one of two nodes for a
> > * very large NR_CPUS.
> > *
> > - * Use PAGE_SIZE as a minimum for smaller configurations.
> > + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> > + * unsigned comparison to -1.
> > */
> > -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> > +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
>
> Maybe it would be easier to read with less braces and '>=' instead of '>'?
> #define CPUMAP_FILE_MAX_BYTES \
> (NR_CPUS * 9 / 32 >= PAGE_SIZE ? NR_CPUS * 9 / 32 - 1 : PAGE_SIZE)
>
> Anyways, this is a good catch. If you think it doesn't worth an
> update, I can take it in bitmap-for-next as-is.
Ah, I screwed in math. '>=' wouldn't work of course...
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 18:09 ` Yury Norov
2022-09-06 18:15 ` Yury Norov
@ 2022-09-06 18:57 ` Phil Auld
2022-09-06 19:11 ` Yury Norov
1 sibling, 1 reply; 7+ messages in thread
From: Phil Auld @ 2022-09-06 18:57 UTC (permalink / raw)
To: Yury Norov
Cc: linux-kernel, Greg Kroah-Hartman, Rafael J . Wysocki, Barry Song,
Tian Tao, feng xiangjun, stable
On Tue, Sep 06, 2022 at 11:09:53AM -0700 Yury Norov wrote:
> On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> > As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> > This leads to very large file sizes:
> >
> > topology$ ls -l
> > total 0
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> > -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> > -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
> >
> > Adjust the inequality to catch the case when NR_CPUS is configured
> > to a small value.
> >
> > Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> > Reported-by: feng xiangjun <fengxj325@gmail.com>
> > Signed-off-by: Phil Auld <pauld@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Yury Norov <yury.norov@gmail.com>
> > Cc: stable@vger.kernel.org
> > Cc: feng xiangjun <fengxj325@gmail.com>
> > ---
> > include/linux/cpumask.h | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> > index bd047864c7ac..7b1349612d6d 100644
> > --- a/include/linux/cpumask.h
> > +++ b/include/linux/cpumask.h
> > @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> > * cover a worst-case of every other cpu being on one of two nodes for a
> > * very large NR_CPUS.
> > *
> > - * Use PAGE_SIZE as a minimum for smaller configurations.
> > + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> > + * unsigned comparison to -1.
> > */
> > -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> > +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
>
> Maybe it would be easier to read with less braces and '>=' instead of '>'?
> #define CPUMAP_FILE_MAX_BYTES \
> (NR_CPUS * 9 / 32 >= PAGE_SIZE ? NR_CPUS * 9 / 32 - 1 : PAGE_SIZE)
>
> Anyways, this is a good catch. If you think it doesn't worth an
> update, I can take it in bitmap-for-next as-is.
>
It would work as
#define CPUMAP_FILE_MAX_BYTES (((NR_CPUS * 9)/32 > PAGE_SIZE) \
? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
Since 4097 > PAGE_SIZE and then you'd get PAGE_SIZE anyway. That is we could just
leave the 1 out of the inequality completely.
If I recall at least some of the parens are needed to make the compiler happy.
I can resend with the above if you want.
Cheers,
Phil
> > ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
> > #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
> >
> > --
> > 2.31.1
>
--
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
2022-09-06 18:57 ` Phil Auld
@ 2022-09-06 19:11 ` Yury Norov
0 siblings, 0 replies; 7+ messages in thread
From: Yury Norov @ 2022-09-06 19:11 UTC (permalink / raw)
To: Phil Auld
Cc: linux-kernel, Greg Kroah-Hartman, Rafael J . Wysocki, Barry Song,
Tian Tao, feng xiangjun, stable
On Tue, Sep 06, 2022 at 02:57:41PM -0400, Phil Auld wrote:
> On Tue, Sep 06, 2022 at 11:09:53AM -0700 Yury Norov wrote:
> > On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote:
> > > As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3.
> > > This leads to very large file sizes:
> > >
> > > topology$ ls -l
> > > total 0
> > > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list
> > > -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id
> > > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list
> > > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id
> > > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list
> > > -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id
> > > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings
> > > -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list
> > >
> > > Adjust the inequality to catch the case when NR_CPUS is configured
> > > to a small value.
> > >
> > > Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist")
> > > Reported-by: feng xiangjun <fengxj325@gmail.com>
> > > Signed-off-by: Phil Auld <pauld@redhat.com>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > > Cc: Yury Norov <yury.norov@gmail.com>
> > > Cc: stable@vger.kernel.org
> > > Cc: feng xiangjun <fengxj325@gmail.com>
> > > ---
> > > include/linux/cpumask.h | 5 +++--
> > > 1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> > > index bd047864c7ac..7b1349612d6d 100644
> > > --- a/include/linux/cpumask.h
> > > +++ b/include/linux/cpumask.h
> > > @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
> > > * cover a worst-case of every other cpu being on one of two nodes for a
> > > * very large NR_CPUS.
> > > *
> > > - * Use PAGE_SIZE as a minimum for smaller configurations.
> > > + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding
> > > + * unsigned comparison to -1.
> > > */
> > > -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
> > > +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \
> >
> > Maybe it would be easier to read with less braces and '>=' instead of '>'?
> > #define CPUMAP_FILE_MAX_BYTES \
> > (NR_CPUS * 9 / 32 >= PAGE_SIZE ? NR_CPUS * 9 / 32 - 1 : PAGE_SIZE)
> >
> > Anyways, this is a good catch. If you think it doesn't worth an
> > update, I can take it in bitmap-for-next as-is.
> >
>
> It would work as
> #define CPUMAP_FILE_MAX_BYTES (((NR_CPUS * 9)/32 > PAGE_SIZE) \
> ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
>
> Since 4097 > PAGE_SIZE and then you'd get PAGE_SIZE anyway. That is we could just
> leave the 1 out of the inequality completely.
>
> If I recall at least some of the parens are needed to make the compiler happy.
>
> I can resend with the above if you want.
Yes, please
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-09-06 19:14 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-09-06 16:04 [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES Phil Auld
2022-09-06 17:02 ` Greg Kroah-Hartman
2022-09-06 17:24 ` Phil Auld
2022-09-06 18:09 ` Yury Norov
2022-09-06 18:15 ` Yury Norov
2022-09-06 18:57 ` Phil Auld
2022-09-06 19:11 ` Yury Norov
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox