linux-kernel - [PATCH v4 4/7] mm/vmalloc: explicitly identify vm_map

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Date:   Wed,  1 Feb 2023 17:13:36 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        stephen.s.brennan@...cle.com, urezki@...il.com, lstoakes@...il.com,
        willy@...radead.org, hch@...radead.org, error27@...il.com,
        Baoquan He <bhe@...hat.com>
Subject: [PATCH v4 4/7] mm/vmalloc: explicitly identify vm_map_ram area when shown in /proc/vmcoreinfo

Now, by marking VMAP_RAM in vmap_area->flags for vm_map_ram area, we can
clearly differentiate it with other vmalloc areas. So identify
vm_map_area area by checking VMAP_RAM of vmap_area->flags when shown
in /proc/vmcoreinfo.

Meanwhile, the code comment above vm_map_ram area checking in s_show()
is not needed any more, remove it here.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 mm/vmalloc.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5a3ea6cb7ec2..e515dbacb0cb 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4232,14 +4232,11 @@ static int s_show(struct seq_file *m, void *p)
 
 	va = list_entry(p, struct vmap_area, list);
 
-	/*
-	 * s_show can encounter race with remove_vm_area, !vm on behalf
-	 * of vmap area is being tear down or vm_map_ram allocation.
-	 */
 	if (!va->vm) {
-		seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
-			(void *)va->va_start, (void *)va->va_end,
-			va->va_end - va->va_start);
+		if (va->flags & VMAP_RAM)
+			seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
+				(void *)va->va_start, (void *)va->va_end,
+				va->va_end - va->va_start);
 
 		goto final;
 	}
-- 
2.34.1