tree a2366a9a09aaa9063b3b4e41eab747fc0c8b29a5
parent d098840e37468fdd0143d8bcfe86bc53627bf96e
author [EMAIL PROTECTED] <[EMAIL PROTECTED]> Tue, 19 Apr 2005 12:00:21 -0700
committer Greg KH <[EMAIL PROTECTED]> Tue, 19 Apr 2005 12:00:21 -0700

[PATCH] aoe 9/12: add note about the need for deadlock-free sk_buff allocation

add note about the need for deadlock-free sk_buff allocation

Signed-off-by: Ed L. Cashin <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>



 aoe/todo.txt |   14 ++++++++++++++
 1 files changed, 14 insertions(+)

Index: Documentation/aoe/todo.txt
===================================================================
--- /dev/null  (tree:ee737c8d61f57e46688504fba2f1e76b845b3085)
+++ a2366a9a09aaa9063b3b4e41eab747fc0c8b29a5/Documentation/aoe/todo.txt  
(mode:100644 sha1:7fee1e1165bcf0a563176fd340be41e9d248e860)
@@ -0,0 +1,14 @@
+There is a potential for deadlock when allocating a struct sk_buff for
+data that needs to be written out to aoe storage.  If the data is
+being written from a dirty page in order to free that page, and if
+there are no other pages available, then deadlock may occur when a
+free page is needed for the sk_buff allocation.  This situation has
+not been observed, but it would be nice to eliminate any potential for
+deadlock under memory pressure.
+
+Because ATA over Ethernet is not fragmented by the kernel's IP code,
+the destructore member of the struct sk_buff is available to the aoe
+driver.  By using a mempool for allocating all but the first few
+sk_buffs, and by registering a destructor, we should be able to
+efficiently allocate sk_buffs without introducing any potential for
+deadlock.
-
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