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

On Thu, Jul 2, 2026 at 2:50 PM hejunhao <[email protected]> wrote:
>
> Gentle ping for this one, and it's ready.

So it requires at least one ACK from a person listed as APEI reviewers
in MAINTAINERS.

> On 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 <[email protected]>
> > ---
> >  drivers/acpi/apei/ghes.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > Changes in V2:
> > 1. update the commit message per suggestion from Xueshuai
> > 2. Add a check to only return failure on the ghes_notify_sea() path,
> >    avoiding impact on other NMI-type GHES handlers.
> > Link to V1 - https://lore.kernel.org/all/[email protected]/
> >
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index 3236a3ce79d6..787664740150 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -1383,8 +1383,16 @@ static int ghes_in_nmi_queue_one_entry(struct ghes *ghes,
> >       ghes_clear_estatus(ghes, &tmp_header, buf_paddr, fixmap_idx);
> >
> >       /* This error has been reported before, don't process it again. */
> > -     if (ghes_estatus_cached(estatus))
> > +     if (ghes_estatus_cached(estatus)) {
> > +             /*
> > +              * Return failure on duplicate SEA entries so that the
> > +              * subsequent SEA handler invocation sends a SIGBUS signal to
> > +              * the task to prevent it from re-entering the handler loop.
> > +              */
> > +             if (is_hest_sync_notify(ghes))
> > +                     rc = -ECANCELED;
> >               goto no_work;
> > +     }
> >
> >       llist_add(&estatus_node->llnode, &ghes_estatus_llist);
> >
>