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Date:   Tue, 11 Jun 2019 16:18:41 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Vladimir Murzin <vladimir.murzin@arm.com>
Cc:     Christoph Hellwig <hch@lst.de>, Palmer Dabbelt <palmer@sifive.com>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        linux-riscv@lists.infradead.org, uclinux-dev@uclinux.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/17] mm: stub out all of swapops.h for !CONFIG_MMU
Message-ID: <20190611141841.GA29151@lst.de>
References: <20190610221621.10938-1-hch@lst.de> <20190610221621.10938-3-hch@lst.de> <516c8def-22db-027c-873d-a943454e33af@arm.com>
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On Tue, Jun 11, 2019 at 11:15:44AM +0100, Vladimir Murzin wrote:
> On 6/10/19 11:16 PM, Christoph Hellwig wrote:
> > The whole header file deals with swap entries and PTEs, none of which
> > can exist for nommu builds.
> 
> Although I agree with the patch, I'm wondering how you get into it?

Without that the RISC-V nommu blows up like this:


In file included from mm/vmscan.c:58:
./include/linux/swapops.h: In function ‘pte_to_swp_entry’:
./include/linux/swapops.h:71:15: error: implicit declaration of function ‘__pte_to_swp_entry’; did you mean ‘pte_to_swp_entry’? [-Werror=implicit-function-declaration]
  arch_entry = __pte_to_swp_entry(pte);
               ^~~~~~~~~~~~~~~~~~
               pte_to_swp_entry
./include/linux/swapops.h:71:13: error: incompatible types when assigning to type ‘swp_entry_t’ {aka ‘struct <anonymous>’} from type ‘int’
  arch_entry = __pte_to_swp_entry(pte);
             ^
./include/linux/swapops.h:72:19: error: implicit declaration of function ‘__swp_type’; did you mean ‘swp_type’? [-Werror=implicit-function-declaration]
  return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
                   ^~~~~~~~~~
                   swp_type
./include/linux/swapops.h:72:43: error: implicit declaration of function ‘__swp_offset’; did you mean ‘swp_offset’? [-Werror=implicit-function-declaration]
  return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
                                           ^~~~~~~~~~~~
                                           swp_offset
./include/linux/swapops.h: In function ‘swp_entry_to_pte’:
./include/linux/swapops.h:83:15: error: implicit declaration of function ‘__swp_entry’; did you mean ‘swp_entry’? [-Werror=implicit-function-declaration]
  arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
               ^~~~~~~~~~~
               swp_entry
./include/linux/swapops.h:83:13: error: incompatible types when assigning to type ‘swp_entry_t’ {aka ‘struct <anonymous>’} from type ‘int’
  arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
             ^
./include/linux/swapops.h:84:9: error: implicit declaration of function ‘__swp_entry_to_pte’; did you mean ‘swp_entry_to_pte’? [-Werror=implicit-function-declaration]
  return __swp_entry_to_pte(arch_entry);
         ^~~~~~~~~~~~~~~~~~
         swp_entry_to_pte
./include/linux/swapops.h:84:9: error: incompatible types when returning type ‘int’ but ‘pte_t’ {aka ‘struct <anonymous>’} was expected
  return __swp_entry_to_pte(arch_entry);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
make[1]: *** [scripts/Makefile.build:278: mm/vmscan.o] Error 1
make: *** [Makefile:1071: mm] Error 2
make: *** Waiting for unfinished jobs....