linux-kernel - [PATCH 6/7] mm/vmalloc: Use a trace_free_vmap_area

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Date:   Mon, 17 Oct 2022 18:02:32 +0200
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 6/7] mm/vmalloc: Use a trace_free_vmap_area_noflush event

It is for a debug purpose and is called when a vmap area
gets freed. This event gives some indication about:
- a start address of released area;
- a current number of outstanding pages;
- a maximum number of allowed outstanding pages.

Cc: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 mm/vmalloc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 912abcd6e8b4..df4fd6674ced 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1822,6 +1822,8 @@ static void drain_vmap_area_work(struct work_struct *work)
  */
 static void free_vmap_area_noflush(struct vmap_area *va)
 {
+	unsigned long nr_lazy_max = lazy_max_pages();
+	unsigned long va_start = va->va_start;
 	unsigned long nr_lazy;
 
 	spin_lock(&vmap_area_lock);
@@ -1839,8 +1841,10 @@ static void free_vmap_area_noflush(struct vmap_area *va)
 		&purge_vmap_area_root, &purge_vmap_area_list);
 	spin_unlock(&purge_vmap_area_lock);
 
+	trace_free_vmap_area_noflush(va_start, nr_lazy, nr_lazy_max);
+
 	/* After this point, we may free va at any time */
-	if (unlikely(nr_lazy > lazy_max_pages()))
+	if (unlikely(nr_lazy > nr_lazy_max))
 		schedule_work(&drain_vmap_work);
 }
 
-- 
2.30.2