Re: [PATCH][RESEND][RFC] Fix 32-bit boot failure due inaccurate page_pool_page_is_pp()

[Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>]

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Helge Deller wrote...

> Commit ee62ce7a1d90 ("page_pool: Track DMA-mapped pages and unmap them when
> destroying the pool") changed PP_MAGIC_MASK from 0xFFFFFFFC to 0xc000007c on
> 32-bit platforms.
> 
> The function page_pool_page_is_pp() uses PP_MAGIC_MASK to identify page pool
> pages, but the remaining bits are not sufficient to unambiguously identify
> such pages any longer.
> 
> So page_pool_page_is_pp() now sometimes wrongly reports pages as page pool
> pages and as such triggers a kernel BUG as it believes it found a page pool
> leak.
> 
> There are patches upcoming where page_pool_page_is_pp() will not depend on
> PP_MAGIC_MASK and instead use page flags to identify page pool pages. Until
> those patches are merged, the easiest temporary fix is to disable the check
> on 32-bit platforms.
> 
> Cc: Jesper Dangaard Brouer <hawk@kernel.org>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Cc: David Hildenbrand <david@redhat.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Cc: Toke Høiland-Jørgensen <toke@redhat.com>
> Cc: Linux Memory Management List <linux-mm@kvack.org>
> Cc: netdev@vger.kernel.org
> Cc: Linux parisc List <linux-parisc@vger.kernel.org>
> Cc: <stable@vger.kernel.org> # v6.15+
> Signed-off-by: Helge Deller <deller@gmx.de>
> Link: https://www.spinics.net/lists/kernel/msg5849623.html
> Fixes: ee62ce7a1d90 ("page_pool: Track DMA-mapped pages and unmap them when destroying the pool")

Tested-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>

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