498166 - malloc_init deadlock due to pthread_atfork

Status: RESOLVED FIXED

(Core :: Memory Allocator, defect)

Description

[Daniel Glöckner]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.8.1.19) Gecko/20081204 SeaMonkey/1.1.14
Build Identifier: http://download.mozilla.org/?product=firefox-3.5b4&os=linux&lang=de

malloc_init_hard calls pthread_atfork which in turn may call malloc => deadlock

Both the nptl and the linuxthreads implementation of pthread_atfork allocate memory on the fly. On nptl we don't observe this bug because pthread_atfork has an initial pool and allocation happens in chunks of 48 entries. On linuxthreads malloc is called everytime.

Reproducible: Always

Steps to Reproduce:
1. run a linux system with linuxthreads instead of nptl
2. start firefox

Actual Results:  
- system becomes idle
- no window, no message in terminal
- process sleeps in pthread_mutex_lock(&init_lock)

Expected Results:  
- a browser window opens

Moving the call to pthread_atfork between

  malloc_initialized = true;

and

  malloc_mutex_unlock(&init_lock);

should fix the bug.

Comment 1

[Leila]

Attachment: Bug-498166-malloc_init-deadlock-due-to-pthread_atfor.patch

We have encountered this problem too, when bringing-up FxOS on a device. The suggested approach from Daniel fixes the problem (attached patch).

Comment 2

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/fbe9d8ab5fca

Comment 3

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/fbe9d8ab5fca