Subject: Re: [PATCH net-next v1] memory-provider: disable building dmabuf mp on !CONFIG_PAGE_POOL

From: Simon Horman <[email-masked]>
Date: Fri, 13 Sep 2024 13:47:20 +0100

On Fri, Sep 13, 2024 at 06:07:45AM +0000, Mina Almasry wrote:
> When CONFIG_TRACEPOINTS=y but CONFIG_PAGE_POOL=n, we end up with this
> build failure that is reported by the 0-day bot:
> 
> ld: vmlinux.o: in function `mp_dmabuf_devmem_alloc_netmems':
> >> (.text+0xc37286): undefined reference to `__tracepoint_page_pool_state_hold'
> >> ld: (.text+0xc3729a): undefined reference to `__SCT__tp_func_page_pool_state_hold'
> >> ld: vmlinux.o:(__jump_table+0x10c48): undefined reference to `__tracepoint_page_pool_state_hold'
> >> ld: vmlinux.o:(.static_call_sites+0xb824): undefined reference to `__SCK__tp_func_page_pool_state_hold'
> 
> The root cause is that in this configuration, traces are enabled but the
> page_pool specific trace_page_pool_state_hold is not registered.
> 
> There is no reason to build the dmabuf memory provider when
> CONFIG_PAGE_POOL is not present, as it's really a provider to the
> page_pool.
> 
> In fact the whole NET_DEVMEM is RX path-only at the moment, so we can
> make the entire config dependent on the PAGE_POOL.
> 
> Note that this may need to be revisited after/while devmem TX is
> added,  as devmem TX likely does not need CONFIG_PAGE_POOL. For now this
> build fix is sufficient.
> 
> Reported-by: kernel test robot <[email-masked]>
> Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/
> Signed-off-by: Mina Almasry <[email-masked]>

Reviewed-by: Simon Horman <[email-masked]>
Tested-by: Simon Horman <[email-masked]> # build-tested