Re: [PATCH v2] ACPI: APEI: Handle repeated SEA error storms

[mawupeng <mawupeng1@huawei.com>]

On 周三 2026-5-27 16:27, Junhao He wrote:
> When hardware memory corruption occurs and a user process accesses the
> corrupted page, the CPU triggers a Synchronous External Abort (SEA).
> The kernel invokes do_sea() to handle the exception, which calls
> memory_failure() to handle the faulty page.
> 
> Scenario 1: Memory Error Interrupt First, then SEA
> The page is already poisoned by the memory error interrupt path. The
> subsequent SEA handler sends a SIGBUS to the task, which accesses the
> poisoned page. This flow is correct.
> 
> Scenario 2: SEA first, then memory error interrupt (problematic scenario)
> If a user task directly accesses corrupted memory through a PFNMAP-style
> mapping (e.g., devmem), the page may still be in the free-buddy state when
> SEA is handled. In this case, memory_failure() will poison the page without
> invoking kill_accessing_process(), and then takes the free-buddy recovery
> path.
> 
> After the CPU returns to the task context, the task re-enters the SEA
> handler due to the same access. However, ghes_estatus_cached() suppresses
> all subsequent entries during the 10-second window, preventing
> ghes_do_proc() from being called. This suppression blocks the
> MF_ACTION_REQUIRED-based SIGBUS delivery, causing the kernel to fail to
> kill the task immediately. Consequently, the process keeps re-entering
> the SEA handler, leading to an SEA storm. Later, the memory error
> interrupt path also cannot kill the task, leaving the system stuck in
> this repeated loop.
> 
> The following error logs are explained using the devmem process:
>   NOTICE:  SEA Handle
>   [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 9
>   [Hardware Error]: event severity: recoverable
>   [Hardware Error]:   section_type: ARM processor error
>   [Hardware Error]:    physical fault address: 0x0000001000093c00
>   [T54990] Memory failure: 0x1000093: recovery action for free buddy page: Recovered
>   [ T9955] EDAC MC0: 1 UE Multi-bit ECC on unknown memory
>            (page:0x1000093 offset:0xc00 grain:1 - APEI location: ...)
>   NOTICE:  SEA Handle
>   NOTICE:  SEA Handle
>   ...
>   ...        ---> SEA storm
>   ...
>   NOTICE:  SEA Handle
>   [ T9955] Memory failure: 0x1000093: already hardware poisoned
>   ghes_print_estatus: 1 callbacks suppressed
>   [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 9
>   [Hardware Error]: event severity: recoverable
>   [Hardware Error]:   section_type: ARM processor error
>   [Hardware Error]:    physical fault address: 0x0000001000093c00
>   [T54990] Memory failure: 0x1000093: already hardware poisoned
>   [T54990] 0x1000093: Sending SIGBUS to devmem:54990 due to hardware memory corruption
> 
> To resolve this, return an error when encountering the same SEA again.
> The subsequent SEA handler invocation uses arm64_notify_die() to send a
> SIGBUS signal to the task, which terminates the process and prevents it
> from re-entering the handler loop.
> 
> Signed-off-by: Junhao He <hejunhao3@h-partners.com>

Reviewed-by: Wupeng Ma <mawupeng1@huawei.com>