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@xxxxxxx>
---
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
--
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