linux-kernel - Re: tipc_init(), WARNING: at arch/x86/mm/highmem_32.c:52, [2.6.24-rc4-git5: Reported regressions from 2.6.23]

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Date:	Sat, 8 Dec 2007 09:54:06 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Matt Mackall <mpm@...enic.com>
cc:	Ingo Molnar <mingo@...e.hu>, "Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <clameter@....com>
Subject: Re: tipc_init(), WARNING: at arch/x86/mm/highmem_32.c:52,
 [2.6.24-rc4-git5: Reported regressions from 2.6.23]



On Sat, 8 Dec 2007, Linus Torvalds wrote:
> 
> But I'll apply it anyway, because it looks "obviously correct" from the 
> standpoint that the _other_��slob user already clears the end result 
> explicitly later on, and we simply should never pass down __GFP_ZERO to 
> the actual page allocator.

Actually, I take that back. The other slob users are different. They share 
pages, this codepath does not.

So I think a more proper solution would be:
 (a) Something like this patch (which includes my previous mm/slub.c 
     change)
 (b) don't warn about atomic GFP_ZERO's - unless they have GFP_HIGHMEM set 
     *too*.

So which warning is it that triggers the bogus error?

		Linus
---
 mm/slob.c |    2 +-
 mm/slub.c |    3 +++
 2 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/mm/slob.c b/mm/slob.c
index ee2ef8a..773a7aa 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -330,7 +330,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
 
 	/* Not enough space: must allocate a new page */
 	if (!b) {
-		b = slob_new_page(gfp, 0, node);
+		b = slob_new_page(gfp & ~__GFP_ZERO, 0, node);
 		if (!b)
 			return 0;
 		sp = (struct slob_page *)virt_to_page(b);
diff --git a/mm/slub.c b/mm/slub.c
index b9f37cb..9c1d9f3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1468,6 +1468,9 @@ static void *__slab_alloc(struct kmem_cache *s,
 	void **object;
 	struct page *new;
 
+	/* We handle __GFP_ZERO in the caller */
+	gfpflags &= ~__GFP_ZERO;
+
 	if (!c->page)
 		goto new_slab;
 
--
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