CVE-2024-57977

In the Linux kernel, the following vulnerability has been resolved:

memcg: fix soft lockup in the OOM process

A soft lockup issue was found in the product with about 56,000 tasks were

in the OOM cgroup, it was traversing them when the soft lockup was

triggered.

watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [VM Thread:1503066]

CPU: 2 PID: 1503066 Comm: VM Thread Kdump: loaded Tainted: G

Hardware name: Huawei Cloud OpenStack Nova, BIOS

RIP: 0010:console_unlock+0x343/0x540

RSP: 0000:ffffb751447db9a0 EFLAGS: 00000247 ORIG_RAX: ffffffffffffff13

RAX: 0000000000000001 RBX: 0000000000000000 RCX: 00000000ffffffff

RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000247

RBP: ffffffffafc71f90 R08: 0000000000000000 R09: 0000000000000040

R10: 0000000000000080 R11: 0000000000000000 R12: ffffffffafc74bd0

R13: ffffffffaf60a220 R14: 0000000000000247 R15: 0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f2fe6ad91f0 CR3: 00000004b2076003 CR4: 0000000000360ee0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

vprintk_emit+0x193/0x280

printk+0x52/0x6e

dump_task+0x114/0x130

mem_cgroup_scan_tasks+0x76/0x100

dump_header+0x1fe/0x210

oom_kill_process+0xd1/0x100

out_of_memory+0x125/0x570

mem_cgroup_out_of_memory+0xb5/0xd0

try_charge+0x720/0x770

mem_cgroup_try_charge+0x86/0x180

mem_cgroup_try_charge_delay+0x1c/0x40

do_anonymous_page+0xb5/0x390

handle_mm_fault+0xc4/0x1f0

This is because thousands of processes are in the OOM cgroup, it takes a

long time to traverse all of them. As a result, this lead to soft lockup

in the OOM process.

To fix this issue, call 'cond_resched' in the 'mem_cgroup_scan_tasks'

function per 1000 iterations. For global OOM, call

'touch_softlockup_watchdog' per 1000 iterations to avoid this issue.