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Date:   Fri, 4 Aug 2023 04:50:13 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-arch@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Mike Rapoport <rppt@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 21/38] powerpc: Implement the new page table range API
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 <20230803233814.GA2515372@dev-arch.thelio-3990X>
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On Thu, Aug 03, 2023 at 04:38:14PM -0700, Nathan Chancellor wrote:
> > -EXPORT_SYMBOL(flush_dcache_icache_page);
> 
> Apologies if this has already been fixed or reported, I searched lore
> and did not find anything. The dropping of this export in combination
> with the conversion above appears to cause ARCH=powerpc allmodconfig to
> fail with:
> 
>   ERROR: modpost: "flush_dcache_icache_folio" [arch/powerpc/kvm/kvm-pr.ko] undefined!
> 
> I don't know if this should be re-exported or not but that does
> obviously resolve the issue.

Well, that was clumsy of me.  I (and the Intel build bot) did test several
build combos, but clearly didn't manage to find a config that showed
this problem.  Andrew, a fix patch for you to integrate, if you would:

diff --git a/arch/powerpc/mm/cacheflush.c b/arch/powerpc/mm/cacheflush.c
index 8760d2223abe..15189592da09 100644
--- a/arch/powerpc/mm/cacheflush.c
+++ b/arch/powerpc/mm/cacheflush.c
@@ -172,6 +172,7 @@ void flush_dcache_icache_folio(struct folio *folio)
 			flush_dcache_icache_phys((pfn + i) * PAGE_SIZE);
 	}
 }
+EXPORT_SYMBOL(flush_dcache_icache_folio);
 
 void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
 {