[Crash-utility] [PATCH] kmem: Add support for SECTION_TAINT_ZONE flag

[HAGIO KAZUHITO(萩尾 一仁)]

Fix for the "kmem {-n|-p}" options on Linux 5.12-rc1 and later kernels
that contain commit 1f90a3477df3f ("mm: teach pfn_to_online_page()
about ZONE_DEVICE section collisions").  Without the patch, the
"kmem -n" option incorrectly shows mem_map addresses containing the
flag in bit 5 as part of the virtual address, and also the "kmem -p"
option shows page structures at wrong position.  With the patch,
the "kmem -n" option displays the new "D" state flag.

Without the patch:
  crash> kmem -n
  ...
  NR      SECTION        CODED_MEM_MAP        MEM_MAP       STATE PFN
  1040  ffff9edf3ffd4100  ffffe2bcc0000010  ffffe2bd42000010  PMOE  34078720
                                        ^                 ^
  crash> kmem -p
      PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
  ffffe2bd42000010 2080000000           400040 1ffffffff 9961471 dead000000000122 referenced,active,error
  ffffe2bd42000050 2080001000           800080 1ffffffff 9961471 dead000000000122 referenced,active,error
  ffffe2bd42000090 2080002000                0 1ffffffff 9961471 dead000000000122 referenced,active,error
                ^^
With the patch:
  crash> kmem -n
  ...
  NR      SECTION        CODED_MEM_MAP        MEM_MAP       STATE PFN
  1040  ffff9edf3ffd4100  ffffe2bcc0000000  ffffe2bd42000000  PMOED 34078720

  crash> kmem -p
      PAGE         PHYSICAL      MAPPING       INDEX CNT FLAGS
  ffffe2bd42000000 2080000000 ffff9ebfc0044100        0  1 97ffffc0000200 slab
  ffffe2bd42000040 2080001000 ffff9ebfc0044400        0  1 97ffffc0000200 slab
  ffffe2bd42000080 2080002000                0        0  1 97ffffc0000000

Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
---
 help.c   | 12 ++++++++----
 memory.c | 15 +++++++++------
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/help.c b/help.c
index e0c84087add3..7734281166eb 100644
--- a/help.c
+++ b/help.c
@@ -6584,10 +6584,14 @@ char *help_kmem[] = {
 "            kernels, the vm_zone_stat, vm_node_stat and vm_numa_stat tables,",
 "            the cumulative page_states counter values if they exist, and/or ",
 "            the cumulative, vm_event_states counter values if they exist.",
-"        -n  display memory node, memory section, and memory block data",
-"            and state; the state of each memory section state is encoded",
-"            as \"P\", \"M\", \"O\" and/or \"E\", meaning SECTION_MARKED_PRESENT,",
-"            SECTION_HAS_MEM_MAP, SECTION_IS_ONLINE and SECTION_IS_EARLY.",
+"        -n  display memory node, memory section, memory block data and state;",
+"            the state of each memory section is shown as the following flags",
+"            respectively:",
+"              \"P\": SECTION_MARKED_PRESENT",
+"              \"M\": SECTION_HAS_MEM_MAP",
+"              \"O\": SECTION_IS_ONLINE",
+"              \"E\": SECTION_IS_EARLY",
+"              \"D\": SECTION_TAINT_ZONE_DEVICE",
 "        -z  displays per-zone memory statistics.",
 "        -o  displays each cpu's offset value that is added to per-cpu symbol",
 "            values to translate them into kernel virtual addresses.",
diff --git a/memory.c b/memory.c
index 8c6bbe409922..7bc9a2cd6d0e 100644
--- a/memory.c
+++ b/memory.c
@@ -17269,12 +17269,13 @@ nr_to_section(ulong nr)
  *      which results in PFN_SECTION_SHIFT equal 6.
  * To sum it up, at least 6 bits are available.
  */
-#define SECTION_MARKED_PRESENT	(1UL<<0)
-#define SECTION_HAS_MEM_MAP	(1UL<<1)
-#define SECTION_IS_ONLINE	(1UL<<2)
-#define SECTION_IS_EARLY	(1UL<<3)
-#define SECTION_MAP_LAST_BIT	(1UL<<4)
-#define SECTION_MAP_MASK	(~(SECTION_MAP_LAST_BIT-1))
+#define SECTION_MARKED_PRESENT		(1UL<<0)
+#define SECTION_HAS_MEM_MAP		(1UL<<1)
+#define SECTION_IS_ONLINE		(1UL<<2)
+#define SECTION_IS_EARLY		(1UL<<3)
+#define SECTION_TAINT_ZONE_DEVICE	(1UL<<4)
+#define SECTION_MAP_LAST_BIT		(1UL<<5)
+#define SECTION_MAP_MASK		(~(SECTION_MAP_LAST_BIT-1))
 
 
 int 
@@ -17372,6 +17373,8 @@ fill_mem_section_state(ulong state, char *buf)
 		bufidx += sprintf(buf + bufidx, "%s", "O");
 	if (state & SECTION_IS_EARLY)
 		bufidx += sprintf(buf + bufidx, "%s", "E");
+	if (state & SECTION_TAINT_ZONE_DEVICE)
+		bufidx += sprintf(buf + bufidx, "%s", "D");
 }
 
 void 
-- 
2.27.0