Re: [PATCH v5 04/18] sparc32: mm: Reduce allocation size for PMD and PTE tables

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

On 5/18/20 7:23 AM, Mike Rapoport wrote:
> On Mon, May 18, 2020 at 02:48:18AM -0700, Guenter Roeck wrote:
>> On 5/18/20 1:37 AM, Will Deacon wrote:
>>> On Sat, May 16, 2020 at 05:07:50PM -0700, Guenter Roeck wrote:
>>>> On Sat, May 16, 2020 at 05:00:50PM -0700, Guenter Roeck wrote:
>>>>> On Mon, May 11, 2020 at 09:41:36PM +0100, Will Deacon wrote:
>>>>>> Now that the page table allocator can free page table allocations
>>>>>> smaller than PAGE_SIZE, reduce the size of the PMD and PTE allocations
>>>>>> to avoid needlessly wasting memory.
>>>>>>
>>>>>> Cc: "David S. Miller" <davem@davemloft.net>
>>>>>> Cc: Peter Zijlstra <peterz@infradead.org>
>>>>>> Signed-off-by: Will Deacon <will@kernel.org>
>>>>>
>>>>> Something in the sparc32 patches in linux-next causes all my sparc32 emulations
>>>>> to crash. bisect points to this patch, but reverting it doesn't help, and neither
>>>>> does reverting the rest of the series.
>>>>>
>>>> Actually, turns out I see the same pattern (lots of scheduling while atomic
>>>> followed by 'killing interrupt handler' in cryptomgr_test) with several
>>>> powerpc boot tests.  I am currently bisecting those crashes. I'll report
>>>> the results here as well as soon as I have it.
>>>
>>> FWIW, I retested my sparc32 patches with PREEMPT=y and I don't see any
>>> issues. However, linux-next is a different story, where I don't get very far
>>> at all:
>>>
>>> BUG: Bad page state in process swapper  pfn:005b4
> 
> This one seems to be due to commit 24aab577764f ("mm: memmap_init:
> iterate over memblock regions rather that check each PFN") and reverting
> it and partially reverting the next cleanup commits makes those
> dissapear. sparc32 boot still fails on today's linux-next and mmotm for me with
> 
> Run /sbin/init as init process
>   with arguments:
>     /sbin/init
>   with environment:
>     HOME=/
>     TERM=linux
> Starting init: /sbin/init exists but couldn't execute it (error -14)
> 
> I've tried to bisect mmotm and I've got the first bad commits in
> different places in the middle of arch/kmap series [1] so I've added Ira
> to CC as well :)
> 
> I'll continue to look into "bad page" on sparc32
> 
> [1] https://lore.kernel.org/dri-devel/20200507150004.1423069-11-ira.weiny@intel.com/
> 
>> Here are the bisect results for ppc:
>>
>> # bad: [bdecf38f228bcca73b31ada98b5b7ba1215eb9c9] Add linux-next specific files for 20200515
>> # good: [2ef96a5bb12be62ef75b5828c0aab838ebb29cb8] Linux 5.7-rc5
>> git bisect start 'HEAD' 'v5.7-rc5'
> 
> ...
> 
>> # good: [9b5aa5b43f957f03a1f4a9aff5f7924e2ebbc011] arch-kmap_atomic-consolidate-duplicate-code-checkpatch-fixes
>> git bisect good 9b5aa5b43f957f03a1f4a9aff5f7924e2ebbc011
>> # bad: [89194ba5ee31567eeee9c81101b334c8e3248198] arch/kmap: define kmap_atomic_prot() for all arch's
>> git bisect bad 89194ba5ee31567eeee9c81101b334c8e3248198
>> # good: [022785d2bea99f8bc2a37b7b6c525eea26f6ac59] arch-kunmap_atomic-consolidate-duplicate-code-checkpatch-fixes
>> git bisect good 022785d2bea99f8bc2a37b7b6c525eea26f6ac59
>> # good: [a13c2f39e3f0519ddee57d26cc66ec70e3546106] arch/kmap: don't hard code kmap_prot values
>> git bisect good a13c2f39e3f0519ddee57d26cc66ec70e3546106
>> # first bad commit: [89194ba5ee31567eeee9c81101b334c8e3248198] arch/kmap: define kmap_atomic_prot() for all arch's
>>
>> I don't know if that is accurate either. Maybe things are so broken
>> that bisect gets confused, or the problem is due to interaction
>> between different patch series.
> 
> My results with the workaround for sparc32 boot look similar:
> 
> # bad: [2bbf0589bfeb27800c730b76eacf34528eee5418] pci: test for unexpectedly disabled bridges
> git bisect bad 2bbf0589bfeb27800c730b76eacf34528eee5418
> # good: [2ef96a5bb12be62ef75b5828c0aab838ebb29cb8] Linux 5.7-rc5
> git bisect good 2ef96a5bb12be62ef75b5828c0aab838ebb29cb8
> # bad: [e4592f53440c6fd2288e2dcb8c6f5b4d9d40fd35] mm-add-debug_wx-support-fix
> git bisect bad e4592f53440c6fd2288e2dcb8c6f5b4d9d40fd35
> # bad: [e4592f53440c6fd2288e2dcb8c6f5b4d9d40fd35] mm-add-debug_wx-support-fix
> git bisect bad e4592f53440c6fd2288e2dcb8c6f5b4d9d40fd35
> # good: [e27369856a2d42ae4d84bc2c4ddac1e696c40d7c] mm: remove the prot argument from vm_map_ram
> git bisect good e27369856a2d42ae4d84bc2c4ddac1e696c40d7c
> # good: [6911f2b29f6daae2c4b51e6a37f794056d8afabd] mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty
> git bisect good 6911f2b29f6daae2c4b51e6a37f794056d8afabd
> # good: [8cef4726f20ae37c3cf3f7a449f5b8a088247a27] hugetlbfs: clean up command line processing
> git bisect good 8cef4726f20ae37c3cf3f7a449f5b8a088247a27
> # good: [94f38895e0a68ceac3ceece6528123ed3129cedd] arch/kmap: ensure kmap_prot visibility
> git bisect good 94f38895e0a68ceac3ceece6528123ed3129cedd
> # skip: [fcc77c28bf9155c681712b25c0f5e6125d10ba2e] kmap: consolidate kmap_prot definitions
> git bisect skip fcc77c28bf9155c681712b25c0f5e6125d10ba2e
> # bad: [175a67be7ee750b2aa2a4a2fedeff18fdce787ac] kmap-consolidate-kmap_prot-definitions-checkpatch-fixes
> git bisect bad 175a67be7ee750b2aa2a4a2fedeff18fdce787ac
> # bad: [54db8ed321d66a00b6c69bbd5bf7c59809b3fd42] drm: vmwgfx: include linux/highmem.h
> git bisect bad 54db8ed321d66a00b6c69bbd5bf7c59809b3fd42
> # bad: [6671299c829d19c6ceb0fd1a14b690f6115c6d3d] arch/kmap: define kmap_atomic_prot() for all arch's
> git bisect bad 6671299c829d19c6ceb0fd1a14b690f6115c6d3d
> # bad: [f800fb6e517710e04391821e4b1908606c8a6b24] arch/kmap: don't hard code kmap_prot values
> git bisect bad f800fb6e517710e04391821e4b1908606c8a6b24
> # first bad commit: [f800fb6e517710e04391821e4b1908606c8a6b24] arch/kmap: don't hard code kmap_prot values
> 
> 

Below is another set of bisect results, from next-20200518. It points to one
of your commits. This is for microblaze (big endian) boot failures.

Guenter

---
# bad: [72bc15d0018ebfbc9c389539d636e2e9a9002b3b] Add linux-next specific files for 20200518
# good: [2ef96a5bb12be62ef75b5828c0aab838ebb29cb8] Linux 5.7-rc5
git bisect start 'HEAD' 'v5.7-rc5'
# good: [b5b9a1a40fcf10db8f140c987b715e6816e1292d] Merge remote-tracking branch 'crypto/master'
git bisect good b5b9a1a40fcf10db8f140c987b715e6816e1292d
# good: [6a349e7cf4cec11b63ca8e3095c990e146f48784] Merge remote-tracking branch 'tip/auto-latest'
git bisect good 6a349e7cf4cec11b63ca8e3095c990e146f48784
# good: [0c5e27cea5e173afc1971ce9a521e022c288548c] Merge remote-tracking branch 'staging/staging-next'
git bisect good 0c5e27cea5e173afc1971ce9a521e022c288548c
# good: [7e90955569a080b17030161db6152917f3b0e061] Merge remote-tracking branch 'hyperv/hyperv-next'
git bisect good 7e90955569a080b17030161db6152917f3b0e061
# good: [c0218a9a3a60cf081f5545302d0fc28a8d68059b] fs/buffer.c: add debug print for __getblk_gfp() stall problem
git bisect good c0218a9a3a60cf081f5545302d0fc28a8d68059b
# good: [bcda3c9d968d3a8b596904fb2ff8009717ffb6ef] Merge branch 'akpm-current/current'
git bisect good bcda3c9d968d3a8b596904fb2ff8009717ffb6ef
# good: [5b271f59a6aee147db3d7137f6132f74977131c1] kernel: use show_stack_loglvl()
git bisect good 5b271f59a6aee147db3d7137f6132f74977131c1
# good: [dec7b12bacc0859e689c4a42714c7bf4d0b98cfd] mm/mmap.c: add more sanity checks to get_unmapped_area()
git bisect good dec7b12bacc0859e689c4a42714c7bf4d0b98cfd
# bad: [feda7bcd5e1846039cc1a999bf4090b1fee890e8] mm: fix build error for mips of process_madvise
git bisect bad feda7bcd5e1846039cc1a999bf4090b1fee890e8
# good: [0533da2f2fa20c28ac5b4573bd6bb0d445638c6a] x86/mm: simplify init_trampoline() and surrounding logic
git bisect good 0533da2f2fa20c28ac5b4573bd6bb0d445638c6a
# bad: [2b166035a0202b90f5860178b8ae43d41a42117f] mm: consolidate pud_index() and pud_offset() definitions
git bisect bad 2b166035a0202b90f5860178b8ae43d41a42117f
# bad: [01f489acfb0783379cc764d503477c0f6df49a0b] mm: consolidate pte_index() and pte_offset_*() definitions
git bisect bad 01f489acfb0783379cc764d503477c0f6df49a0b
# bad: [c57a43e52bf5fdc4152bb17db6e9c5d35569dcfd] mm: pgtable: add shortcuts for accessing kernel PMD and PTE
git bisect bad c57a43e52bf5fdc4152bb17db6e9c5d35569dcfd
# first bad commit: [c57a43e52bf5fdc4152bb17db6e9c5d35569dcfd] mm: pgtable: add shortcuts for accessing kernel PMD and PTE