The patch titled
cpuset: update cpuset_zones_allowed comment
has been added to the -mm tree. Its filename is
cpuset-update-cpuset_zones_allowed-comment.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: cpuset: update cpuset_zones_allowed comment
From: Paul Jackson <pj@xxxxxxx>
Update the kernel/cpuset.c:cpuset_zone_allowed() comment.
The rule for when mm/page_alloc.c should call cpuset_zone_allowed()
was intended to be:
Don't call cpuset_zone_allowed() if you can't sleep, unless you
pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
the code that might scan up ancestor cpusets and sleep.
The explanation of this rule in the comment above cpuset_zone_allowed() was
stale, as a result of a restructuring of some __alloc_pages() code in
November 2005.
Rewrite that comment ...
Signed-off-by: Paul Jackson <pj@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/cpuset.c | 24 +++++++++++++++---------
1 files changed, 15 insertions(+), 9 deletions(-)
diff -puN kernel/cpuset.c~cpuset-update-cpuset_zones_allowed-comment kernel/cpuset.c
--- devel/kernel/cpuset.c~cpuset-update-cpuset_zones_allowed-comment 2006-05-18 02:08:06.000000000 -0700
+++ devel-akpm/kernel/cpuset.c 2006-05-18 02:08:06.000000000 -0700
@@ -2231,19 +2231,25 @@ static const struct cpuset *nearest_excl
* So only GFP_KERNEL allocations, if all nodes in the cpuset are
* short of memory, might require taking the callback_mutex mutex.
*
- * The first loop over the zonelist in mm/page_alloc.c:__alloc_pages()
- * calls here with __GFP_HARDWALL always set in gfp_mask, enforcing
- * hardwall cpusets - no allocation on a node outside the cpuset is
- * allowed (unless in interrupt, of course).
- *
- * The second loop doesn't even call here for GFP_ATOMIC requests
- * (if the __alloc_pages() local variable 'wait' is set). That check
- * and the checks below have the combined affect in the second loop of
- * the __alloc_pages() routine that:
+ * The first call here from mm/page_alloc:get_page_from_freelist()
+ * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, so
+ * no allocation on a node outside the cpuset is allowed (unless in
+ * interrupt, of course).
+ *
+ * The second pass through get_page_from_freelist() doesn't even call
+ * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
+ * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
+ * in alloc_flags. That logic and the checks below have the combined
+ * affect that:
* in_interrupt - any node ok (current task context irrelevant)
* GFP_ATOMIC - any node ok
* GFP_KERNEL - any node in enclosing mem_exclusive cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
+ *
+ * Rule:
+ * Don't call cpuset_zone_allowed() if you can't sleep, unless you
+ * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
+ * the code that might scan up ancestor cpusets and sleep.
**/
int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
_
Patches currently in -mm which might be from pj@xxxxxxx are
cpuset-might-sleep-checking-zones-allowed-fix.patch
cpuset-update-cpuset_zones_allowed-comment.patch
proc-dont-lock-task_structs-indefinitely.patch
proc-dont-lock-task_structs-indefinitely-task_mmu-small-fixes.patch
-
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