Comment 23 for bug 1652348

Okay... I can't help but think I made a mistake somewhere in the bisecting process, but it seems to have isolated fd4b5fa6e3487d15ede746f92601af008b2abbc0 as the bad commit

$ git bisect log
# bad: [6d4f0a79e5a307b6fd3ee3cc5bbb2fcb701b09db] UBUNTU: Ubuntu-4.4.0-57.78
# good: [40a98f0e91bcc062babd017732cbf7cb20cf39fd] UBUNTU: Ubuntu-4.4.0-51.72
git bisect start 'Ubuntu-4.4.0-57.78' 'Ubuntu-4.4.0-51.72'
# bad: [cd29d2303e86529c089b1c292480c05e7a24bd16] drm/i915: Respect alternate_ddc_pin for all DDI ports
git bisect bad cd29d2303e86529c089b1c292480c05e7a24bd16
# bad: [617dec606ff9e43e64a06daef83e17da0035340a] drm/exynos: fix error handling in exynos_drm_subdrv_open
git bisect bad 617dec606ff9e43e64a06daef83e17da0035340a
# bad: [0dbd2050197ea4dd59f8957b72981cb7d2cfab1c] usb: gadget: function: u_ether: don't starve tx request queue
git bisect bad 0dbd2050197ea4dd59f8957b72981cb7d2cfab1c
# bad: [f3f9de1bd9a63b633946226ba23392ad44e2badf] i2c: core: fix NULL pointer dereference under race condition
git bisect bad f3f9de1bd9a63b633946226ba23392ad44e2badf
# good: [a0678a6643bf688bccce3c298a4a110af10988fc] ipv6: correctly add local routes when lo goes up
git bisect good a0678a6643bf688bccce3c298a4a110af10988fc
# good: [a0ae41d8ee0549161174a39d60f7316b67a87cae] Bluetooth: btusb: Add support for 0cf3:e009
git bisect good a0ae41d8ee0549161174a39d60f7316b67a87cae
# good: [d5d9494d2092a7e571dee635ca254075912355c1] thinkpad_acpi: Add support for HKEY version 0x200
git bisect good d5d9494d2092a7e571dee635ca254075912355c1
# bad: [a6e674fa25854a7dafc59555d508855ea8fe3eaa] i2c: xgene: Avoid dma_buffer overrun
git bisect bad a6e674fa25854a7dafc59555d508855ea8fe3eaa
# bad: [fd4b5fa6e3487d15ede746f92601af008b2abbc0] mnt: Add a per mount namespace limit on the number of mounts
git bisect bad fd4b5fa6e3487d15ede746f92601af008b2abbc0
# first bad commit: [fd4b5fa6e3487d15ede746f92601af008b2abbc0] mnt: Add a per mount namespace limit on the number of mounts

From a layman perspective, it doesn't seem like that could possibly cause the bug.

I guess one quick way forward, rather than repeat the whole bisecting process, is to completely reset the repository, bring it up to date, verify the bug still exists, and then revert this specific commit and see if the bug goes away.