----- On Oct 17, 2018, at 11:00 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:

----- On Oct 16, 2018, at 8:27 PM, Sergey Senozhatsky
sergey.senozhatsky.work@gmail.com wrote:

quoted

On (10/16/18 14:30), Steven Rostedt wrote:

quoted

quoted

+void vm_unmap_user_ram(const void *mem, unsigned int count)
+{
+	unsigned long size = (unsigned long)count << PAGE_SHIFT;
+	unsigned long addr = (unsigned long)mem;
+	struct vmap_area *va;
+
+	might_sleep();
+	BUG_ON(!addr);
+	BUG_ON(addr < VMALLOC_START);
+	BUG_ON(addr > VMALLOC_END);
+	BUG_ON(!PAGE_ALIGNED(addr));
+
+	debug_check_no_locks_freed(mem, size);
+	va = find_vmap_area(addr);
+	BUG_ON(!va);
+	free_unmap_vmap_area(va);
+}
+EXPORT_SYMBOL(vm_unmap_user_ram);
+

Noticing this from Sergey's question in another patch, why are you
using BUG_ON()? That's rather extreme and something we are trying to
avoid adding more of (I still need to remove the BUG_ON()s I've added
over ten years ago). I don't see why all these BUG_ON's can't be turned
into:

+1

quoted

	if (WARN_ON(x))
		return;

Given that this somewhat MM-related, I'd may be say VM_WARN_ON().

I notice that VM_WARN_ON() casts the result of WARN_ON() to (void), so it
cannot be used in a if () statement.

VM_WARN_ON() will only warn if CONFIG_DEBUG_VM is set.

Is it really what we want ?

Thanks,

Mathieu

Good point, will do!

So I'll do one cleanup patch for vm_unmap_ram(), and I'll modify the new
vm_unmap_user_ram().

Thanks,

Mathieu

quoted

	-ss

--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com