In the Linux kernel, the following vulnerability has been resolved:
Revert "sched/fair: Make sure to try to detach at least one movable task"
This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06.
b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if
all tasks examined to that point were pinned. The goal of the patch was
to make it more likely to be able to detach a task buried in a long list
of pinned tasks. However, this has the unfortunate side effect of
creating an O(n) iteration in detach_tasks(), as we now must fully
iterate every task on a cpu if all or most are pinned. Since this load
balance code is done with rq lock held, and often in softirq context, it
is very easy to trigger hard lockups. We observed such hard lockups with
a user who affined O(10k) threads to a single cpu.
When I discussed this with Vincent he initially suggested that we keep
the limit on the number of tasks to detach, but increase the number of
tasks we can search. However, after some back and forth on the mailing
list, he recommended we instead revert the original patch, as it seems
likely no one was actually getting hit by the original issue.
Metrics
Affected Vendors & Products
References
History
Wed, 13 Nov 2024 02:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Redhat
Redhat enterprise Linux |
|
CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9 |
|
Vendors & Products |
Redhat
Redhat enterprise Linux |
Wed, 11 Sep 2024 13:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Fri, 16 Aug 2024 18:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Weaknesses | CWE-99 |
Thu, 08 Aug 2024 21:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
References |
| |
Metrics |
threat_severity
|
threat_severity
|
Thu, 08 Aug 2024 15:15:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
Weaknesses | CWE-667 | |
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
Vendors & Products |
Linux
Linux linux Kernel |
|
Metrics |
cvssV3_1
|
Wed, 07 Aug 2024 15:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Description | In the Linux kernel, the following vulnerability has been resolved: Revert "sched/fair: Make sure to try to detach at least one movable task" This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06. b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if all tasks examined to that point were pinned. The goal of the patch was to make it more likely to be able to detach a task buried in a long list of pinned tasks. However, this has the unfortunate side effect of creating an O(n) iteration in detach_tasks(), as we now must fully iterate every task on a cpu if all or most are pinned. Since this load balance code is done with rq lock held, and often in softirq context, it is very easy to trigger hard lockups. We observed such hard lockups with a user who affined O(10k) threads to a single cpu. When I discussed this with Vincent he initially suggested that we keep the limit on the number of tasks to detach, but increase the number of tasks we can search. However, after some back and forth on the mailing list, he recommended we instead revert the original patch, as it seems likely no one was actually getting hit by the original issue. | |
Title | Revert "sched/fair: Make sure to try to detach at least one movable task" | |
References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published: 2024-08-07T15:14:31.019Z
Updated: 2024-11-05T09:38:58.562Z
Reserved: 2024-07-30T07:40:12.254Z
Link: CVE-2024-42245
Vulnrichment
Updated: 2024-09-11T12:42:24.180Z
NVD
Status : Analyzed
Published: 2024-08-07T16:15:47.230
Modified: 2024-08-08T14:53:19.530
Link: CVE-2024-42245
Redhat