Hi Matthew,

On Wed, Mar 10, 2021 at 06:55:30PM +0000, Matthew Wilcox (Oracle) wrote:
> There's no need to give the page an address_space.  Leaving the
> page->mapping as NULL will cause the VM to handle set_page_dirty()
> the same way that it's handled now, and that was the only reason to
> set the address_space in the first place.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: William Kucharski <william.kucharski@oracle.com>

This patch in mainline as commit ccf953d8f3d6 ("fb_defio: Remove custom
address_space_operations") causes my Hyper-V based VM to no longer make
it to a graphical environment.

$ git bisect log
# bad: [6efb943b8616ec53a5e444193dccf1af9ad627b5] Linux 5.13-rc1
# good: [9f4ad9e425a1d3b6a34617b8ea226d56a119a717] Linux 5.12
git bisect start 'v5.13-rc1' 'v5.12'
# bad: [71a5cc28e88b0db69c3f83d4061ad4cc684af09f] Merge tag 'mfd-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd
git bisect bad 71a5cc28e88b0db69c3f83d4061ad4cc684af09f
# good: [2a19866b6e4cf554b57660549d12496ea84aa7d7] Merge tag '5.12-rc-smb3-fixes-part1' of git://git.samba.org/sfrench/cifs-2.6
git bisect good 2a19866b6e4cf554b57660549d12496ea84aa7d7
# bad: [a1a1ca70deb3ec600eeabb21de7f3f48aaae5695] Merge tag 'drm-misc-next-fixes-2021-04-22' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
git bisect bad a1a1ca70deb3ec600eeabb21de7f3f48aaae5695
# good: [2cbcb78c9ee5520c8d836c7ff57d1b60ebe8e9b7] Merge tag 'amd-drm-next-5.13-2021-03-23' of https://gitlab.freedesktop.org/agd5f/linux into drm-next
git bisect good 2cbcb78c9ee5520c8d836c7ff57d1b60ebe8e9b7
# bad: [9c0fed84d5750e1eea6c664e073ffa2534a17743] Merge tag 'drm-intel-next-2021-04-01' of git://anongit.freedesktop.org/drm/drm-intel into drm-next
git bisect bad 9c0fed84d5750e1eea6c664e073ffa2534a17743
# bad: [1539f71602edf09bb33666afddc5a781c42e768d] Merge tag 'drm-misc-next-2021-04-01' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
git bisect bad 1539f71602edf09bb33666afddc5a781c42e768d
# good: [2f835b5dd8f7fc1e58d73fc2cd2ec33c2b054036] Merge tag 'topic/i915-gem-next-2021-03-26' of ssh://git.freedesktop.org/git/drm/drm into drm-next
git bisect good 2f835b5dd8f7fc1e58d73fc2cd2ec33c2b054036
# bad: [c42712c6e9bea042ea9696713024af7417f5ce18] drm/bridge/analogix/anx6345: Cleanup on errors in anx6345_bridge_attach()
git bisect bad c42712c6e9bea042ea9696713024af7417f5ce18
# bad: [dc659a4e852b591771fc2e5abb60f4455b0cf316] drm/probe-helper: Check epoch counter in output_poll_execute()
git bisect bad dc659a4e852b591771fc2e5abb60f4455b0cf316
# good: [5e7222a3674ea7422370779884dd53aabe9e4a9d] drm/panel-simple: Undo enable if HPD never asserts
git bisect good 5e7222a3674ea7422370779884dd53aabe9e4a9d
# good: [67cc24ac17fe2a2496456c8ca281ef89f7a6fd89] drm: panel: simple: Set enable delay for BOE NV110WTM-N61
git bisect good 67cc24ac17fe2a2496456c8ca281ef89f7a6fd89
# bad: [ccf953d8f3d68e85e577e843fdcde8872b0a9769] fb_defio: Remove custom address_space_operations
git bisect bad ccf953d8f3d68e85e577e843fdcde8872b0a9769
# good: [8613385cb2856e2ee9c4efb1f95eeaca0e1a0963] dma-fence: Document recoverable page fault implications
git bisect good 8613385cb2856e2ee9c4efb1f95eeaca0e1a0963
# first bad commit: [ccf953d8f3d68e85e577e843fdcde8872b0a9769] fb_defio: Remove custom address_space_operations

I did verify that I do not see the issue fixed with next-20210528. I
have attached the output of 'journalctl -k' from v5.13-rc3 and
next-20210528, they do not seem to provide any smoking gun to me but I
am not really sure what to look for. I am happy to provide any further
information or do any debugging as you see fit.

Cheers,
Nathan