In -current (and 6.4), chrome repeatedly attempts to mmap a large linear
area of memory for WASM/WebAssembly and it always fails. WASM JIT avoids
using the system malloc/free, opting instead for their own "Heartbleed
accelerating custom allocator".
Despite the horribleness, this feature is being increasingly used by
default if the browser advertises this misfeature as supported, many
sites will fallback if it is unavailable. Unfortunately, they *DO NOT*
fallback if WASM fails to allocate memory. You simply get broken, half-
working websites. :-(
For example, the popular video streaming platform (twitch.tv) will show
a black box where the stream should be. The error is not obvious unless
you check the browsers Javascript console:
Uncaught RangeError: WebAssembly.Memory(): could not allocate memory
at wasmworker.min.js:51
at blob:https://www.twitch.tv/2af8520d-25ad-4f42-bc94-497265c25c62:6
(index):1 Script error
After hours of searching, I found the magic knob to disable WASM in
chrome: '--js-flags=--noexpose_wasm'
There's no UI way that I can find to disable it, so you'll need to
add a shell alias or put it in your window managers config.
Note: Firefox is also not saved from this insanity, WASM will often
fail there as well.. unless datasize is cranked to infinity and beyond.
-Bryan.
Here's the ktrace(1)/kdump(1) for chrome:
60738 chrome CALL
mmap(0x1f46f5fa0000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x1f46f5fa0000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x208a1b2f0000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x208a1b2f0000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2f8546810000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2f8546810000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x29b16e690000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x29b16e690000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2cfe5ed40000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2cfe5ed40000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2b67a9e90000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome CALL
mmap(0x2b67a9e90000,0x280000000,0<PROT_NONE>,0x1002<MAP_PRIVATE|MAP_ANON>,-1,0)
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
60738 chrome RET mmap -1 errno 12 Cannot allocate memory
