linux-kernel - [PATCH v8 12/16] mm/debug: print vm_refcnt state when dumping the vma

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Message-ID: <20250109023025.2242447-13-surenb@google.com>
Date: Wed,  8 Jan 2025 18:30:21 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: akpm@...ux-foundation.org
Cc: peterz@...radead.org, willy@...radead.org, liam.howlett@...cle.com, 
	lorenzo.stoakes@...cle.com, mhocko@...e.com, vbabka@...e.cz, 
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	linux-doc@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
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Subject: [PATCH v8 12/16] mm/debug: print vm_refcnt state when dumping the vma

vm_refcnt encodes a number of useful states:
- whether vma is attached or detached
- the number of current vma readers
- presence of a vma writer
Let's include it in the vma dump.

Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
 mm/debug.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mm/debug.c b/mm/debug.c
index 8d2acf432385..325d7bf22038 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -178,6 +178,17 @@ EXPORT_SYMBOL(dump_page);
 
 void dump_vma(const struct vm_area_struct *vma)
 {
+#ifdef CONFIG_PER_VMA_LOCK
+	pr_emerg("vma %px start %px end %px mm %px\n"
+		"prot %lx anon_vma %px vm_ops %px\n"
+		"pgoff %lx file %px private_data %px\n"
+		"flags: %#lx(%pGv) refcnt %x\n",
+		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_mm,
+		(unsigned long)pgprot_val(vma->vm_page_prot),
+		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
+		vma->vm_file, vma->vm_private_data,
+		vma->vm_flags, &vma->vm_flags, refcount_read(&vma->vm_refcnt));
+#else
 	pr_emerg("vma %px start %px end %px mm %px\n"
 		"prot %lx anon_vma %px vm_ops %px\n"
 		"pgoff %lx file %px private_data %px\n"
@@ -187,6 +198,7 @@ void dump_vma(const struct vm_area_struct *vma)
 		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 		vma->vm_file, vma->vm_private_data,
 		vma->vm_flags, &vma->vm_flags);
+#endif
 }
 EXPORT_SYMBOL(dump_vma);
 
-- 
2.47.1.613.gc27f4b7a9f-goog