How to patch kernel or upgrade to kernel patch-2.6.26.3
am using centos 5.1

i given the command patch -p1 <patch-2.6.26.3

after that one message comming i.e

patching file a/Documentation/ftrace.txt
can't find file to patch at input line 1364
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
|diff --git a/Documentation/networking/udplite.txt b/Documentation/networking/udplite.txt
|index 3870f28..855d8da 100644
|--- a/Documentation/networking/udplite.txt
|+++ b/Documentation/networking/udplite.txt
--------------------------
File to patch:

what is this file to patch ????
any help and suggestion pls.

Yes it exactly means that paths/files are not matching...
I am not sure what you are trying to do.... But I can explain the basics of patch...

Let us say I have linux2.6.23/kernel/drivers/abcd.c and there is a patch available for that file then this will be with reference to linux2.6.23 folder....... So, what you can do is copy the patch into linux2.6.23 directory and then do
patch -p1 < "patch name"

Arguments to -p mainly suggests that how many Slashes (/) are to be omitted from the line
diff --git a/Documentation/networking/udplite.txt b/Documentation/networking/udplite.txt
found in patch file..........

If it doesnt help, post your exact directory structure and initial lines of patch file........

Kernel patches have to be applied to the kernel source and then a new kernel compiled to use it on a running system.