From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Uladzislau Rezki <urezki@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
Lorenzo Stoakes <lstoakes@gmail.com>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
Zhen Lei <thunder.leizhen@huaweicloud.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
rcu@vger.kernel.org, Zqiang <qiang.zhang1211@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
linux-mm@kvack.org
Subject: [PATCH v2 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug
Date: Thu, 31 Aug 2023 17:18:25 +0000 [thread overview]
Message-ID: <20230831171827.2625016-1-joel@joelfernandes.org> (raw)
It is unsafe to dump vmalloc area information when trying to do so from
some contexts. Add a safer trylock version of the same function to do a
best-effort VMA finding and use it from vmalloc_dump_obj().
[apply test robot feedback on unused function fix.]
Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: rcu@vger.kernel.org
Cc: Zqiang <qiang.zhang1211@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
v1->v2: Apply review tags and test robot feedback.
mm/vmalloc.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 93cf99aba335..f09e882ae3b8 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1865,6 +1865,20 @@ struct vmap_area *find_vmap_area(unsigned long addr)
return va;
}
+#ifdef CONFIG_PRINTK
+static struct vmap_area *find_vmap_area_trylock(unsigned long addr)
+{
+ struct vmap_area *va;
+
+ if (!spin_trylock(&vmap_area_lock))
+ return NULL;
+ va = __find_vmap_area(addr, &vmap_area_root);
+ spin_unlock(&vmap_area_lock);
+
+ return va;
+}
+#endif
+
static struct vmap_area *find_unlink_vmap_area(unsigned long addr)
{
struct vmap_area *va;
@@ -2671,6 +2685,29 @@ struct vm_struct *find_vm_area(const void *addr)
return va->vm;
}
+/**
+ * try_to_find_vm_area - find a continuous kernel virtual area
+ * @addr: base address
+ *
+ * This function is the same as find_vm_area() except that it is
+ * safe to call if vmap_area_lock is already held and returns NULL
+ * if it is. See comments in find_vmap_area() for other details.
+ *
+ * Return: the area descriptor on success or %NULL on failure.
+ */
+#ifdef CONFIG_PRINTK
+static struct vm_struct *try_to_find_vm_area(const void *addr)
+{
+ struct vmap_area *va;
+
+ va = find_vmap_area_trylock((unsigned long)addr);
+ if (!va)
+ return NULL;
+
+ return va->vm;
+}
+#endif
+
/**
* remove_vm_area - find and remove a continuous kernel virtual area
* @addr: base address
@@ -4277,7 +4314,7 @@ bool vmalloc_dump_obj(void *object)
struct vm_struct *vm;
void *objp = (void *)PAGE_ALIGN((unsigned long)object);
- vm = find_vm_area(objp);
+ vm = try_to_find_vm_area(objp);
if (!vm)
return false;
pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
--
2.42.0.rc2.253.gd59a3bf2b4-goog
next reply other threads:[~2023-08-31 17:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 17:18 Joel Fernandes (Google) [this message]
2023-08-31 17:18 ` [PATCH v2 2/2] rcu: Dump vmalloc memory info safely Joel Fernandes (Google)
2023-08-31 19:47 ` [PATCH v2 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug Uladzislau Rezki
2023-09-01 0:19 ` Joel Fernandes
2023-09-01 0:33 ` Joel Fernandes
2023-09-01 12:48 ` Uladzislau Rezki
2023-09-01 16:41 ` Joel Fernandes
2023-09-04 8:29 ` Uladzislau Rezki
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