[REGRESSION][BISECTED] Hibernation: WARNING at kernel/power/main.c:48 pm_restrict_gfp_mask (was: "[PATCH v1] PM: hibernate: Restrict GFP mask in hibernation_snapshot()")

[Askar Safin <safinaskar@gmail.com>]

"Rafael J. Wysocki" <rafael@kernel.org>:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Commit 12ffc3b1513e ("PM: Restrict swap use to later in the suspend
> sequence") incorrectly removed a pm_restrict_gfp_mask() call from
> hibernation_snapshot(), so memory allocations involving swap are not
> prevented from being carried out in this code path any more which may
> lead to serious breakage.

#regzbot introduced: 449c9c02537a146ac97ef962327a221e21c9cab3

This commit introduced regression: now I see WARNING every time when
I hibernate. The bug reproduces both on real hardware and in Qemu.

Here is script I used to reproduce this bug in Qemu:
https://zerobin.net/?aadae7117a208c0a#Xh8aI5+u3pyk+vKwET7j+yXolLeoSLe/AedcvnNeCLs=

Here is resulting log (dmesg) on current master (43e9ad0c55a3):
https://zerobin.net/?471d17d0632e7f85#uYne0yUu+rP4KnDbOFFqtCrcDIi6UpQz2uIQw85lcdQ=

Here is the most interesting part:

[    1.735001] PM: Image saving progress:  90%
[    1.746611] PM: Image saving progress: 100%
[    1.747208] PM: Image saving done
[    1.747403] PM: hibernation: Wrote 30164 kbytes in 0.13 seconds (232.03 MB/s)
[    1.747837] PM: Image size after compression: 8908 kbytes
[    1.748190] PM: S|
[    1.750351] ------------[ cut here ]------------
[    1.750627] WARNING: CPU: 0 PID: 1 at kernel/power/main.c:48 pm_restrict_gfp_mask+0x3b/0x40

On real hardware exactly same thing happens (i. e. WARNING at kernel/power/main.c:48 pm_restrict_gfp_mask).

-- 
Askar Safin