Re: [PATCH v3 1/8] mm: Cleanup faultaround and finish_fault() codepaths

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Jan 14, 2021 at 05:59:27PM +0000, Will Deacon wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> 
> alloc_set_pte() has two users with different requirements: in the
> faultaround code, it called from an atomic context and PTE page table
> has to be preallocated. finish_fault() can sleep and allocate page table
> as needed.
> 
> PTL locking rules are also strange, hard to follow and overkill for
> finish_fault().
> 
> Let's untangle the mess. alloc_set_pte() has gone now. All locking is
> explicit.
> 
> The price is some code duplication to handle huge pages in faultaround
> path, but it should be fine, having overall improvement in readability.
> 
> Link: https://lore.kernel.org/r/20201229132819.najtavneutnf7ajp@box
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> [will: s/from from/from/ in comment; spotted by willy]
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  fs/xfs/xfs_file.c       |   6 +-
>  include/linux/mm.h      |  12 ++-
>  include/linux/pgtable.h |  11 +++
>  mm/filemap.c            | 177 ++++++++++++++++++++++++++---------
>  mm/memory.c             | 199 ++++++++++++----------------------------
>  5 files changed, 213 insertions(+), 192 deletions(-)
> 

When building microblaze:mmu_defconfig:

mm/filemap.c: In function 'filemap_map_pages':
mm/filemap.c:3153:3: error: implicit declaration of function 'update_mmu_cache'; did you mean 'update_mmu_tlb'?

Bisect log attached.

Guenter

---
# bad: [a4bfd8d46ac357c12529e4eebb6c89502b03ecc9] Add linux-next specific files for 20210209
# good: [92bf22614b21a2706f4993b278017e437f7785b3] Linux 5.11-rc7
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# bad: [4053c8a4d3b53205272aa16b65a5b7ed1a3a5b3e] Merge remote-tracking branch 'arm-soc/for-next'
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# good: [dfb8870aed6ad71fb7e378274521bf68a7d465cb] Merge branch 'arm/dt' into for-next
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# good: [edc55d8409542cd05d5c17203615a162cddbcb4c] Merge branch 'arm/drivers' into for-next
git bisect good edc55d8409542cd05d5c17203615a162cddbcb4c
# good: [d1bbc35fcab28668c8992c4d5777234b794d7306] arm64: hibernate: add __force attribute to gfp_t casting
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# bad: [fb01b86f47a44f0c03278a7cc78ece8415898ed0] Merge branches 'for-next/cosmetic', 'for-next/crypto', 'for-next/faultaround', 'for-next/from-tip/irq/urgent', 'for-next/kexec', 'for-next/misc', 'for-next/mm', 'for-next/perf', 'for-next/random', 'for-next/rng', 'for-next/selftests', 'for-next/stacktrace', 'for-next/topology' and 'for-next/vdso' into for-next/core
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# good: [750d43b4a79e5f3767ee1db933b42abdf967ce1e] dt-bindings: arm: add Cortex-A78 binding
git bisect good 750d43b4a79e5f3767ee1db933b42abdf967ce1e
# good: [0188a894c390e51475274ece76b4d601782d709e] arm64: vmlinux.ld.S: add assertion for tramp_pg_dir offset
git bisect good 0188a894c390e51475274ece76b4d601782d709e
# bad: [3f98a28cc37253269b4104cf95a51f7716a2eb97] mm/nommu: Fix return type of filemap_map_pages()
git bisect bad 3f98a28cc37253269b4104cf95a51f7716a2eb97
# bad: [742d33729a0df11c9d8d4625dbf21dd20cdefd44] mm: Move immutable fields of 'struct vm_fault' into anonymous struct
git bisect bad 742d33729a0df11c9d8d4625dbf21dd20cdefd44
# bad: [46bdb4277f98e70d0c91f4289897ade533fe9e80] mm: Allow architectures to request 'old' entries when prefaulting
git bisect bad 46bdb4277f98e70d0c91f4289897ade533fe9e80
# bad: [f9ce0be71d1fbb038ada15ced83474b0e63f264d] mm: Cleanup faultaround and finish_fault() codepaths
git bisect bad f9ce0be71d1fbb038ada15ced83474b0e63f264d
# first bad commit: [f9ce0be71d1fbb038ada15ced83474b0e63f264d] mm: Cleanup faultaround and finish_fault() codepaths