1786259 - Site no longer loads in Safe Mode (gfx.e10s.font-list.shared = false) on Windows

Status: VERIFIED FIXED

(Core :: Layout: Text and Fonts, defect, P2)

Description

[Kestrel]

STR:

1. Enter Safe Mode or set gfx.e10s.font-list.shared = false on Windows 10.
2. Visit https://razerid.razer.com.

Loading permanently stalls on a blank page with "Read razerid-assets.razerzone.com" at the bottom. The flame graph has the following stack:

NtWaitForAlertByThreadId
RtlAcquireSRWLockExclusive
gfxFontFamily::AddFontEntry(RefPtr<gfxFontEntry>)
gfxPlatformFontList::AddWithLegacyFamilyName(nsTSubstring<char> const&, gfxFontEntry*, FontVisibility)
gfxFontFamily::CheckForLegacyFamilyNames(gfxPlatformFontList*)
gfxPlatformFontList::FindAndAddFamiliesLocked(nsPresContext*, mozilla::StyleGenericFontFamily, nsTSubstring<char> const&, nsTArray<FamilyAndGeneric>*, gfxPlatformFontList::FindFamiliesFlags, gfxFontStyle*, nsAtom*, double)
gfxDWriteFontList::FindAndAddFamiliesLocked(nsPresContext*, mozilla::StyleGenericFontFamily, nsTSubstring<char> const&, nsTArray<FamilyAndGeneric>*, gfxPlatformFontList::FindFamiliesFlags, gfxFontStyle*, nsAtom*, double)
gfxFontGroup::BuildFontList()

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=95428e3fa48ed01f0ee28cc2cbb5c88ead83c933&tochange=a38c915b806d90681a68d37a97494e1f2c9eac38

Regressed by Bug 1756474

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

:jfkthame, since you are the author of the regressor, bug 1756474, could you take a look?
For more information, please visit auto_nag documentation.

Comment 2

[Taddes Korris [:taddes]]

Hey Jonathan, just checking if there are any updates on this one and if you'd managed to take a look.

Comment 3

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1786259 - Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=#gfx-reviewers

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/34da92947068
Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=gfx-reviewers,aosmond

Comment 5

[Jonathan Kew [:jfkthame]]

Comment on attachment 9294609 [details]
Bug 1786259 - Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=#gfx-reviewers

Beta/Release Uplift Approval Request

• User impact if declined: Possible content-process hang (deadlock) when running in Safe Mode (depending on font configuration and site content)
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: STR in comment 0.
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Simple change reduces the scope of the read-lock to the minimum required, to eliminate risk of deadlocking in a subsequently-called method.
• String changes made/needed:
• Is Android affected?: No

Comment 6

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/34da92947068

Comment 7

[Alexandru Trif, Desktop QA [:atrif]]

Hello! Reproduced the issue with Firefox 106.0a1 (20220822190304) on Windows 10x64. Loading https://razerid.razer.com/ in Safe mode or with gfx.e10s.font-list.shared = false will result in a permanent stall on a blank page.

The issue is verified fixed with Firefox 106.0a1 (20220914213649) on Windows 10x64, macOS 11 and Ubuntu 21.1. The https://razerid.razer.com/ page loads as expected while in Safe mode or while gfx.e10s.font-list.shared = false.

Comment 8

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9294609 [details]
Bug 1786259 - Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=#gfx-reviewers

Fixes a safe mode deadlock on some sites. Approved for 105.0.2.

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-release/rev/e47ddf4a282b

Comment 10

[Ryan VanderMeulen [:RyanVM]]

Seems like it would be a good idea to get this onto ESR as well, especially as it grafts cleanly. WDYT, Jonathan? :)

Comment 11

[Jonathan Kew [:jfkthame]]

Comment on attachment 9294609 [details]
Bug 1786259 - Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=#gfx-reviewers

ESR Uplift Approval Request

• If this is not a sec:{high,crit} bug, please state case for ESR consideration: Potential deadlock on some sites (depending on fonts installed / used) in "Safe" Mode
• User impact if declined:
• Fix Landed on Version:
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Simple patch to make a local copy of data to avoid risk of deadlock during processing.

Comment 12

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9294609 [details]
Bug 1786259 - Avoid potential deadlock via AddWithLegacyFamilyName when shared-fontlist is disabled (incl. safe mode). r=#gfx-reviewers

Approved for 102.4esr.

Comment 13

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-esr102/rev/5fbc2b5e30eb

Comment 14

[Ryan VanderMeulen [:RyanVM]]

Added to the 105.0.2 release notes:

Fixed a possible deadlock when loading some sites in Troubleshoot Mode

Comment 15

[Alexandru Trif, Desktop QA [:atrif]]

Verified fixed with Firefox 105.0.2(20221003135607) and Firefox 102.04.0esr(20221003174742) from comment 13 on Windows 10x64, macOS 11 and Ubuntu 22.04. The https://razerid.razer.com/ webpage is loaded as expected after setting gfx.e10s.font-list.shared:false or after entering Troubleshoot Mode.