Re: [PATCH] mm, kasan: don't poison boot memory

On 2/25/2021 3:53 AM, Mike Rapoport wrote:

Hi George,

quoted

On 2/24/2021 5:37 AM, Mike Rapoport wrote:

quoted

On Tue, Feb 23, 2021 at 04:46:28PM -0500, George Kennedy wrote:

quoted

Mike,

Still no luck.

[   30.193723] iscsi: registered transport (iser)
[   30.195970] iBFT detected.
[   30.196571] BUG: unable to handle page fault for address: ffffffffff240004

Hmm, we cannot set ibft_addr to early pointer to the ACPI table.
Let's try something more disruptive and move the reservation back to
iscsi_ibft_find.c.

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 7bdc0239a943..c118dd54a747 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c

@@ -1551,6 +1551,7 @@ void __init acpi_boot_table_init(void)
   	if (acpi_disabled)
   		return;
+#if 0
   	/*
   	 * Initialize the ACPI boot-time table parser.
   	 */

@@ -1558,6 +1559,7 @@ void __init acpi_boot_table_init(void)
   		disable_acpi();
   		return;
   	}
+#endif
   	acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d883176ef2ce..c615ce96c9a2 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c

@@ -570,16 +570,6 @@ void __init reserve_standard_io_resources(void)
   }
-static __init void reserve_ibft_region(void)
-{
-	unsigned long addr, size = 0;
-
-	addr = find_ibft_region(&size);
-
-	if (size)
-		memblock_reserve(addr, size);
-}
-
   static bool __init snb_gfx_workaround_needed(void)
   {
   #ifdef CONFIG_PCI

@@ -1032,6 +1022,12 @@ void __init setup_arch(char **cmdline_p)
   	 */
   	find_smp_config();
+	/*
+	 * Initialize the ACPI boot-time table parser.
+	 */
+	if (acpi_table_init())
+		disable_acpi();
+
   	reserve_ibft_region();
   	early_alloc_pgt_buf();

diff --git a/drivers/firmware/iscsi_ibft_find.c b/drivers/firmware/iscsi_ibft_find.c
index 64bb94523281..01be513843d6 100644
--- a/drivers/firmware/iscsi_ibft_find.c
+++ b/drivers/firmware/iscsi_ibft_find.c

@@ -47,7 +47,25 @@ static const struct {
   #define VGA_MEM 0xA0000 /* VGA buffer */
   #define VGA_SIZE 0x20000 /* 128kB */
-static int __init find_ibft_in_mem(void)
+static void __init *acpi_find_ibft_region(void)
+{
+	int i;
+	struct acpi_table_header *table = NULL;
+	acpi_status status;
+
+	if (acpi_disabled)
+		return NULL;
+
+	for (i = 0; i < ARRAY_SIZE(ibft_signs) && !ibft_addr; i++) {
+		status = acpi_get_table(ibft_signs[i].sign, 0, &table);
+		if (ACPI_SUCCESS(status))
+			return table;
+	}
+
+	return NULL;
+}
+
+static void __init *find_ibft_in_mem(void)
   {
   	unsigned long pos;
   	unsigned int len = 0;

@@ -70,35 +88,44 @@ static int __init find_ibft_in_mem(void)
   				/* if the length of the table extends past 1M,
   				 * the table cannot be valid. */
   				if (pos + len <= (IBFT_END-1)) {
-					ibft_addr = (struct acpi_table_ibft *)virt;
   					pr_info("iBFT found at 0x%lx.\n", pos);
-					goto done;
+					return virt;
   				}
   			}
   		}
   	}
-done:
-	return len;
+
+	return NULL;
   }
+
+static void __init *find_ibft(void)
+{
+	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
+	 * only use ACPI for this */
+	if (!efi_enabled(EFI_BOOT))
+		return find_ibft_in_mem();
+	else
+		return acpi_find_ibft_region();
+}
+
   /*
    * Routine used to find the iSCSI Boot Format Table. The logical
    * kernel address is set in the ibft_addr global variable.
    */
-unsigned long __init find_ibft_region(unsigned long *sizep)
+void __init reserve_ibft_region(void)
   {
-	ibft_addr = NULL;
+	struct acpi_table_ibft *table;
+	unsigned long size;
-	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
-	 * only use ACPI for this */
+	table = find_ibft();
+	if (!table)
+		return;
-	if (!efi_enabled(EFI_BOOT))
-		find_ibft_in_mem();
-
-	if (ibft_addr) {
-		*sizep = PAGE_ALIGN(ibft_addr->header.length);
-		return (u64)virt_to_phys(ibft_addr);
-	}
+	size = PAGE_ALIGN(table->header.length);
+	memblock_reserve(virt_to_phys(table), size);
-	*sizep = 0;
-	return 0;
+	if (efi_enabled(EFI_BOOT))
+		acpi_put_table(&table->header);
+	else
+		ibft_addr = table;
   }

diff --git a/include/linux/iscsi_ibft.h b/include/linux/iscsi_ibft.h
index b7b45ca82bea..da813c891990 100644
--- a/include/linux/iscsi_ibft.h
+++ b/include/linux/iscsi_ibft.h

@@ -26,13 +26,9 @@ extern struct acpi_table_ibft *ibft_addr;
    * mapped address is set in the ibft_addr variable.
    */
   #ifdef CONFIG_ISCSI_IBFT_FIND
-unsigned long find_ibft_region(unsigned long *sizep);
+void reserve_ibft_region(void);
   #else
-static inline unsigned long find_ibft_region(unsigned long *sizep)
-{
-	*sizep = 0;
-	return 0;
-}
+static inline void reserve_ibft_region(void) {}
   #endif
   #endif /* ISCSI_IBFT_H */

Still no luck Mike,

We're back to the original problem where the only thing that worked was to
run "SetPageReserved(page)" before calling "kmap(page)". The page is being
"freed" before ibft_init() is called as a result of the recent buddy page
freeing changes.

I keep missing some little details each time :(

No worries. Thanks for all your help. Does this patch go on top of your 
previous patch or is it standalone?

George

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