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BACKPORT: FROMGIT: mm/page_alloc: add trace event for per-zone lowmem reserve setup

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This commit introduces the `mm_setup_per_zone_lowmem_reserve` trace
event,which provides detailed insights into the kernel's per-zone lowmem
reserve configuration.

The trace event provides precise timestamps, allowing developers to

1. Correlate lowmem reserve changes with specific kernel events and
   able to diagnose unexpected kswapd or direct reclaim behavior triggered
   by dynamic changes in lowmem reserve.

2. Know memory allocation failures that occur due to insufficient
   lowmem reserve, by precisely correlating allocation attempts with
   reserve adjustments.

Link: https://lkml.kernel.org/r/20250308034606.2036033-3-liumartin@google.com
Signed-off-by: Martin Liu <liumartin@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Bug: 396115949
(cherry picked from commit a293aba4a584709889f77a0ad0c45746aecf1b9f
 https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
Change-Id: I271fc260ec60645230681bf0afbcd10d84453c88
Signed-off-by: Martin Liu <liumartin@google.com>
This commit is contained in:
Martin Liu
2025-03-08 03:46:01 +00:00
parent 9d6305174c
commit 95baed1663
2 changed files with 29 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
include/trace/events/kmem.h
View File

@@ -375,6 +375,33 @@ TRACE_EVENT(mm_setup_per_zone_wmarks,
__entry->watermark_promo)
);
TRACE_EVENT(mm_setup_per_zone_lowmem_reserve,
TP_PROTO(struct zone *zone, struct zone *upper_zone, long lowmem_reserve),
TP_ARGS(zone, upper_zone, lowmem_reserve),
TP_STRUCT__entry(
__field(int, node_id)
__string(name, zone->name)
__string(upper_name, upper_zone->name)
__field(long, lowmem_reserve)
),
TP_fast_assign(
__entry->node_id = zone->zone_pgdat->node_id;
__assign_str(name, zone->name);
__assign_str(upper_name, zone->name);
__entry->lowmem_reserve = lowmem_reserve;
),
TP_printk("node_id=%d zone name=%s upper_zone name=%s lowmem_reserve_pages=%ld",
__entry->node_id,
__get_str(name),
__get_str(upper_name),
__entry->lowmem_reserve)
);
/*
* Required for uniquely and securely identifying mm in rss_stat tracepoint.
*/

2
mm/page_alloc.c
View File

@@ -9007,6 +9007,8 @@ static void setup_per_zone_lowmem_reserve(void)
zone->lowmem_reserve[j] = 0;
else
zone->lowmem_reserve[j] = managed_pages / ratio;
trace_mm_setup_per_zone_lowmem_reserve(zone, upper_zone,
zone->lowmem_reserve[j]);
}
}
}