From 95baed16639c0928fac06f2a10af71798bba3c01 Mon Sep 17 00:00:00 2001 From: Martin Liu Date: Sat, 8 Mar 2025 03:46:01 +0000 Subject: [PATCH] BACKPORT: FROMGIT: mm/page_alloc: add trace event for per-zone lowmem reserve setup 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 Acked-by: David Rientjes Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Steven Rostedt Signed-off-by: Andrew Morton 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 --- include/trace/events/kmem.h | 27 +++++++++++++++++++++++++++ mm/page_alloc.c | 2 ++ 2 files changed, 29 insertions(+) diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 09b58792762d..5b1578a4a89e 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -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. */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ca88e02fdbe4..aecf77d9a672 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -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]); } } }