KPF_WAITERS indicates tasks are waiting for a page lock or writeback.
This might be false-positive, in this case next unlock will clear it.
This looks like worth information not only for kernel hacking.
In tool page-types in non-raw mode treat KPF_WAITERS without
KPF_LOCKED and KPF_WRITEBACK as false-positive and hide it.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
fs/proc/page.c | 1 +
include/uapi/linux/kernel-page-flags.h | 1 +
tools/vm/page-types.c | 7 +++++++
3 files changed, 9 insertions(+)
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 1491918a33c3..b9312e1124af 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -159,6 +159,7 @@ u64 stable_page_flags(struct page *page)
u |= 1 << KPF_IDLE;
u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
+ u |= kpf_copy_bit(k, KPF_WAITERS, PG_waiters);
u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
if (PageTail(page) && PageSlab(compound_head(page)))
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index fa139841ec18..1118a028f2b3 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -35,6 +35,7 @@
#define KPF_BALLOON 23
#define KPF_ZERO_PAGE 24
#define KPF_IDLE 25
+#define KPF_WAITERS 26
#endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index a8783f48f77f..76d880b768b5 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -107,6 +107,7 @@
static const char * const page_flag_names[] = {
[KPF_LOCKED] = "L:locked",
+ [KPF_WAITERS] = "Q:waiters",
[KPF_ERROR] = "E:error",
[KPF_REFERENCED] = "R:referenced",
[KPF_UPTODATE] = "U:uptodate",
@@ -498,6 +499,12 @@ static uint64_t well_known_flags(uint64_t flags)
if ((flags & BITS_COMPOUND) && !(flags & BIT(HUGE)))
flags &= ~BITS_COMPOUND;
+ /* Treat WAITERS without LOCKED or WRITEBACK as false-postive */
+ if ((flags & (BIT(WAITERS) |
+ BIT(LOCKED) |
+ BIT(WRITEBACK))) == BIT(WAITERS))
+ flags &= ~BIT(WAITERS);
+
return flags;
}
--
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