Re: [PATCH v3 3/3] mce, acpi/apei: Soft-offline a page on firmware GHES notification

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On 07/03/2013 08:14 PM, Borislav Petkov wrote:
On Tue, Jul 02, 2013 at 05:02:48PM +0530, Naveen N. Rao wrote:
Here is the updated patch. I also added printk_ratelimit() in line with the
rest of the GHES code.

Thanks,
Naveen

--
If the firmware indicates in GHES error data entry that the error threshold
has exceeded for a corrected error event, then we try to soft-offline the
page. This could be called in interrupt context, so we queue this up similar
to how we handle memory failure scenarios.


Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
---
  drivers/acpi/apei/ghes.c |   38 +++++++++++++++++++++++++++++---------
  include/linux/mm.h       |    1 +
  mm/memory-failure.c      |    5 ++++-
  3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index fcd7d91..74ef688 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -409,6 +409,34 @@ static void ghes_clear_estatus(struct ghes *ghes)
  	ghes->flags &= ~GHES_TO_CLEAR;
  }

+static void ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata, int sev)
+{
+#ifdef CONFIG_ACPI_APEI_MEMORY_FAILURE
+	int sec_sev = ghes_severity(gdata->error_severity);
+	struct cper_sec_mem_err *mem_err;
+	mem_err = (struct cper_sec_mem_err *)(gdata+1);

A newline here please. Also, spaces around '+'.

This was borrowed from existing code in ghes_do_proc(), but yes, let me make this change.


+	if (sec_sev == GHES_SEV_CORRECTED &&
+	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED) &&
+	    (mem_err->validation_bits & CPER_MEM_VALID_PHYSICAL_ADDRESS)) {
+		unsigned long pfn;

This pfn is defined twice, move it up to the beginning of the function.

Ok.


+		pfn = mem_err->physical_addr >> PAGE_SHIFT;
+		if (pfn_valid(pfn))
+			memory_failure_queue(pfn, 0, MF_SOFT_OFFLINE);
+		else if (printk_ratelimit())
+			pr_warning(FW_WARN GHES_PFX

WARNING: Prefer printk_ratelimited or pr_<level>_ratelimited to printk_ratelimit
#35: FILE: drivers/acpi/apei/ghes.c:425:
+               else if (printk_ratelimit())

Please run your patches through checkpatch.pl first.

I did run checkpatch.pl, but chose to ignore this warning. ghes.c uses printk_ratelimit() [hence "in line with the rest of the ghes code" in patch description] and I felt using it is better in this scenario given there will be other messages being printed by the rest of the APEI code. So, rate-limiting these messages globally seems better rather than doing locally using pr_warn_ratelimited()


This requested change will even simplify the code (ontop of your patch):

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 74ef6882bca9..87e11d468f6b 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -422,10 +422,10 @@ static void ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata, int
  		pfn = mem_err->physical_addr >> PAGE_SHIFT;
  		if (pfn_valid(pfn))
  			memory_failure_queue(pfn, 0, MF_SOFT_OFFLINE);
-		else if (printk_ratelimit())
-			pr_warning(FW_WARN GHES_PFX
-			"Invalid address in generic error data: %#llx\n",
-			mem_err->physical_addr);
+		else
+			pr_warn_ratelimited(FW_WARN GHES_PFX
+					    "Invalid address in generic error data: %#llx\n",
+					    mem_err->physical_addr);
  	}
  	if (sev == GHES_SEV_RECOVERABLE &&
  	    sec_sev == GHES_SEV_RECOVERABLE &&
---



+			"Invalid address in generic error data: %#llx\n",
+			mem_err->physical_addr);
+	}
+	if (sev == GHES_SEV_RECOVERABLE &&
+	    sec_sev == GHES_SEV_RECOVERABLE &&
+	    mem_err->validation_bits & CPER_MEM_VALID_PHYSICAL_ADDRESS) {
+		unsigned long pfn;
+		pfn = mem_err->physical_addr >> PAGE_SHIFT;
+		memory_failure_queue(pfn, 0, 0);
+	}
+#endif
+}
+
  static void ghes_do_proc(struct ghes *ghes,
  			 const struct acpi_hest_generic_status *estatus)
  {
@@ -428,15 +456,7 @@ static void ghes_do_proc(struct ghes *ghes,
  			apei_mce_report_mem_error(sev == GHES_SEV_CORRECTED,
  						  mem_err);
  #endif
-#ifdef CONFIG_ACPI_APEI_MEMORY_FAILURE
-			if (sev == GHES_SEV_RECOVERABLE &&
-			    sec_sev == GHES_SEV_RECOVERABLE &&
-			    mem_err->validation_bits & CPER_MEM_VALID_PHYSICAL_ADDRESS) {
-				unsigned long pfn;
-				pfn = mem_err->physical_addr >> PAGE_SHIFT;
-				memory_failure_queue(pfn, 0, 0);
-			}
-#endif
+			ghes_handle_memory_failure(gdata, sev);
  		}
  #ifdef CONFIG_ACPI_APEI_PCIEAER
  		else if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e0c8528..958e9efd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1784,6 +1784,7 @@ enum mf_flags {
  	MF_COUNT_INCREASED = 1 << 0,
  	MF_ACTION_REQUIRED = 1 << 1,
  	MF_MUST_KILL = 1 << 2,
+	MF_SOFT_OFFLINE = 1 << 3,
  };
  extern int memory_failure(unsigned long pfn, int trapno, int flags);
  extern void memory_failure_queue(unsigned long pfn, int trapno, int flags);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ceb0c7f..0d6717e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1286,7 +1286,10 @@ static void memory_failure_work_func(struct work_struct *work)
  		spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
  		if (!gotten)
  			break;
-		memory_failure(entry.pfn, entry.trapno, entry.flags);
+		if (entry.flags & MF_SOFT_OFFLINE)
+			soft_offline_page(pfn_to_page(entry.pfn), entry.flags);
+		else
+			memory_failure(entry.pfn, entry.trapno, entry.flags);

The rest looks ok to me.

I'm guessing this has been tested by injecting errors...?

Yes, at least partially to ensure this works ;)

Thanks,
Naveen

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