Re: __vmalloc with GFP_ATOMIC causes 'sleeping from invalid context'

[Giridhar Pemmasani <giri@lmc.cs.sunysb.edu>]

On Mon, 22 May 2006 16:10:45 +1000, Nick Piggin <nickpiggin@yahoo.com.au> said:

   > Nick Piggin wrote:
  >> Giridhar Pemmasani wrote:
  >> 
  >>> On Mon, 22 May 2006 11:53:55 +1000, Nick Piggin
  >>> <nickpiggin@yahoo.com.au> said:
  >>> 
  >>> > Giridhar Pemmasani wrote: >> If __vmalloc is called in atomic
  >>> context with GFP_ATOMIC flags, >> __get_vm_area_node is called,
  >>> which calls kmalloc_node with >> GFP_KERNEL flags. This causes
  >>> 'sleeping function called from >> invalid context at
  >>> mm/slab.c:2729' with 2.6.16-rc4 kernel. A >> simple solution is
  >>> to use
  >>> 
  >>> > I can't see what would cause this in either 2.6.16-rc4 or >
  >>> 2.6.17-rc4.  What is the line?
  >>> 
  >>> If someone calls __vmalloc in atomic context (with GFP_ATOMIC
  >>> flags):
  >> 
  >> 
  >> OK I misunderstood your comment. I was looking for the caller.
  >> Hmm, page_alloc.c does, but I don't know that it needs to be
  >> atomic -- what happens if we just make that allocation
  >> GFP_KERNEL?
  >> 

   > OTOH, it doesn't seem to be particularly wrong to allow __vmalloc
   > GFP_ATOMIC allocations. The correct fix is to pass the gfp_mask
   > to kmalloc: if you're worried about breaking the API, introduce a
   > new __get_vm_area_node_mask() and implement __get_vm_area_node()
   > as a simple wrapper that passes in GFP_KERNEL.

Here is an attempt at this. I also made __get_vm_area_node static.

Signed-off-by: Giridhar Pemmasani <giri@lmc.cs.sunysb.edu>

diff -Naur linux.orig/include/linux/vmalloc.h linux/include/linux/vmalloc.h
--- linux.orig/include/linux/vmalloc.h	2006-05-22 02:45:23.000000000 -0400
+++ linux/include/linux/vmalloc.h	2006-05-22 02:45:38.000000000 -0400
@@ -3,6 +3,7 @@
 
 #include <linux/spinlock.h>
 #include <asm/page.h>		/* pgprot_t */
+#include <linux/gfp.h>
 
 /* bits in vm_struct->flags */
 #define VM_IOREMAP	0x00000001	/* ioremap() and friends */
@@ -52,8 +53,15 @@
 extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
 extern struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
 					unsigned long start, unsigned long end);
-extern struct vm_struct *get_vm_area_node(unsigned long size,
-					unsigned long flags, int node);
+extern struct vm_struct *get_vm_area_node_mask(unsigned long size,
+					       unsigned long flags, int node,
+					       gfp_t gfp_mask);
+static inline struct vm_struct *get_vm_area_node(unsigned long size,
+						 unsigned long flags, int node)
+{
+	return get_vm_area_node_mask(size, flags, node, GFP_KERNEL);
+}
+
 extern struct vm_struct *remove_vm_area(void *addr);
 extern struct vm_struct *__remove_vm_area(void *addr);
 extern int map_vm_area(struct vm_struct *area, pgprot_t prot,
diff -Naur linux.orig/mm/vmalloc.c linux/mm/vmalloc.c
--- linux.orig/mm/vmalloc.c	2006-05-19 01:22:00.000000000 -0400
+++ linux/mm/vmalloc.c	2006-05-22 02:45:49.000000000 -0400
@@ -157,8 +157,9 @@
 	return err;
 }
 
-struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
-				unsigned long start, unsigned long end, int node)
+static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
+					    unsigned long start, unsigned long end,
+					    int node, gfp_t gfp_mask)
 {
 	struct vm_struct **p, *tmp, *area;
 	unsigned long align = 1;
@@ -177,7 +178,7 @@
 	addr = ALIGN(start, align);
 	size = PAGE_ALIGN(size);
 
-	area = kmalloc_node(sizeof(*area), GFP_KERNEL, node);
+	area = kmalloc_node(sizeof(*area), gfp_mask, node);
 	if (unlikely(!area))
 		return NULL;
 
@@ -233,7 +234,7 @@
 struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
 				unsigned long start, unsigned long end)
 {
-	return __get_vm_area_node(size, flags, start, end, -1);
+	return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL);
 }
 
 /**
@@ -251,9 +252,11 @@
 	return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
 }
 
-struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags, int node)
+struct vm_struct *get_vm_area_node_mask(unsigned long size, unsigned long flags,
+					int node, gfp_t gfp_mask)
 {
-	return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node);
+	return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
+				  gfp_mask);
 }
 
 /* Caller must hold vmlist_lock */
@@ -471,7 +474,7 @@
 	if (!size || (size >> PAGE_SHIFT) > num_physpages)
 		return NULL;
 
-	area = get_vm_area_node(size, VM_ALLOC, node);
+	area = get_vm_area_node_mask(size, VM_ALLOC, node, gfp_mask);
 	if (!area)
 		return NULL;
 

Thanks,
Giri