Synchronous error was detected as a result of user-space process accessing a 2-bit uncorrected error. The CPU will take a synchronous error exception such as Synchronous External Abort (SEA) on Arm64. The kernel will queue a memory_failure() work which poisons the related page, unmaps the page, and then sends a SIGBUS to the process, so that a system wide panic can be avoided.
However, no memory_failure() work will be queued when abnormal synchronous errors occur. These errors can include situations such as invalid PA, unexpected severity, no memory failure config support, invalid GUID section, etc. In such case, the user-space process will trigger SEA again. This loop can potentially exceed the platform firmware threshold or even trigger a kernel hard lockup, leading to a system reboot.
Fix it by performing a force kill if no memory_failure() work is queued for synchronous errors.
Signed-off-by: Shuai Xue xueshuai@linux.alibaba.com --- drivers/acpi/apei/ghes.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index ab2a82cb1b0b..f832ffc5a88d 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -717,6 +717,15 @@ static bool ghes_do_proc(struct ghes *ghes, } }
+ /* + * If no memory failure work is queued for abnormal synchronous + * errors, do a force kill. + */ + if (sync && !queued) { + pr_err("Sending SIGBUS to current task due to memory error not recovered"); + force_sig(SIGBUS); + } + return queued; }