[PATCH 1/4] x86/mce: Do not enter deferred errors into the generic pool twice

From: Borislav Petkov
Date: Tue Nov 24 2015 - 02:42:07 EST


From: Tony Luck <tony.luck@xxxxxxxxx>

We used to have a special ring buffer for deferred errors that was used
to mark problem pages. We replaced that with a generic pool. Then later
converted mce_log() to also use the same pool. As a result, we end up
adding all deferred errors to the pool twice.

Rearrange this code. Make sure to set the m.severity and m.usable_addr
fields for deferred errors. Then if flags and mca_cfg.dont_log_ce mean
we call mce_log() we are done, because that will add this entry to the
generic pool.

If we skipped mce_log(), then we still want to take action for the
deferred error, so add to the pool.

Change the name of the boolean "error_logged" to "error_seen", we should
set it whether of not we logged an error because the return value from
machine_check_poll() is used to decide whether storms have subsided or
not.

Reported-by: Gong Chen <gong.chen@xxxxxxxxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/3165a4989dcb45fc0306438d40d0cf2ace429c4c.1447280215.git.tony.luck@xxxxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index c5b0d562dbf5..6531cb46803c 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -567,7 +567,7 @@ DEFINE_PER_CPU(unsigned, mce_poll_count);
*/
bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
{
- bool error_logged = false;
+ bool error_seen = false;
struct mce m;
int severity;
int i;
@@ -601,6 +601,8 @@ bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
(m.status & (mca_cfg.ser ? MCI_STATUS_S : MCI_STATUS_UC)))
continue;

+ error_seen = true;
+
mce_read_aux(&m, i);

if (!(flags & MCP_TIMESTAMP))
@@ -608,17 +610,10 @@ bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)

severity = mce_severity(&m, mca_cfg.tolerant, NULL, false);

- /*
- * In the cases where we don't have a valid address after all,
- * do not add it into the ring buffer.
- */
if (severity == MCE_DEFERRED_SEVERITY && memory_error(&m)) {
if (m.status & MCI_STATUS_ADDRV) {
m.severity = severity;
m.usable_addr = mce_usable_address(&m);
-
- if (!mce_gen_pool_add(&m))
- mce_schedule_work();
}
}

@@ -626,9 +621,16 @@ bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
* Don't get the IP here because it's unlikely to
* have anything to do with the actual error location.
*/
- if (!(flags & MCP_DONTLOG) && !mca_cfg.dont_log_ce) {
- error_logged = true;
+ if (!(flags & MCP_DONTLOG) && !mca_cfg.dont_log_ce)
mce_log(&m);
+ else if (m.usable_addr) {
+ /*
+ * Although we skipped logging this, we still want
+ * to take action. Add to the pool so the registered
+ * notifiers will see it.
+ */
+ if (!mce_gen_pool_add(&m))
+ mce_schedule_work();
}

/*
@@ -644,7 +646,7 @@ bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)

sync_core();

- return error_logged;
+ return error_seen;
}
EXPORT_SYMBOL_GPL(machine_check_poll);

--
2.3.5

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