This patch applies on top of my patch of March 26, entitled "cpusets special case GFP_ATOMIC allocs". It tones down my panic'y commentary.
My commentary shouldn't imply that failed GFP_ATOMICs should lead to, or normally lead to, panics. Even though there are a few panic() calls following failed GFP_ATOMIC allocs, this is not the usual or desired result of a failed GFP_ATOMIC. The kernel will probably drop some detail on the floor and keep on working. Thanks to Nick Piggin for noticing (I hope this answers his point.) Signed-off-by: Paul Jackson <[EMAIL PROTECTED]> Index: 2.6.12-pj/Documentation/cpusets.txt =================================================================== --- 2.6.12-pj.orig/Documentation/cpusets.txt 2005-03-27 22:48:14.000000000 -0800 +++ 2.6.12-pj/Documentation/cpusets.txt 2005-03-27 22:48:22.000000000 -0800 @@ -264,11 +264,11 @@ Nodes when using hotplug to add or remov There is a second exception to the above. GFP_ATOMIC requests are kernel internal allocations that must be satisfied, immediately. -The kernel may panic if such a requested page is not allocated. -If such a request cannot be satisfied within the cpusets allowed -memory, then we relax the cpuset boundaries and allow any page in -the system to satisfy a GFP_ATOMIC request. It is better to violate -the cpuset constraints than it is to panic the kernel. +The kernel may drop some request, in rare cases even panic, if a +GFP_ATOMIC alloc fails. If the request cannot be satisfied within +the current tasks cpuset, then we relax the cpuset, and look for +memory anywhere we can find it. It's better to violate the cpuset +than stress the kernel. To start a new job that is to be contained within a cpuset, the steps are: Index: 2.6.12-pj/mm/page_alloc.c =================================================================== --- 2.6.12-pj.orig/mm/page_alloc.c 2005-03-27 22:48:14.000000000 -0800 +++ 2.6.12-pj/mm/page_alloc.c 2005-03-27 22:48:42.000000000 -0800 @@ -782,7 +782,7 @@ __alloc_pages(unsigned int gfp_mask, uns * coming from realtime tasks to go deeper into reserves * * This is the last chance, in general, before the goto nopage. - * Ignore cpuset if GFP_ATOMIC (!wait) - better that than panic. + * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc. */ for (i = 0; (z = zones[i]) != NULL; i++) { if (!zone_watermark_ok(z, order, z->pages_min, -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson <[EMAIL PROTECTED]> 1.650.933.1373, 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/