System Information
Operating system: Ubuntu 20.04.3 LTS
Graphics card: GeForce RTX 2060

Blender Version
Broken: 3.0.0, f1cca3055776, master, 2021-12-02
Worked: 2.93.7, a5b7f9dc9011, master, 2021-12-14

Note: I also downloaded the December 29th 3.0.0 daily build from https://builder.blender.org/download/daily/ but it has the same hash as the official release, the only difference seems to be the build date:

$ ./blender --version
Blender 3.0.0
	build date: 2021-12-29
	build time: 00:34:14
	build commit date: 2021-12-02
	build commit time: 18:35
	build hash: f1cca3055776
	build platform: Linux
	build type: release

Short description of error

Any action that pushes Blender's RSS near the 4.7GiB mark consistently causes Blender to crash on my very generic Ubuntu 20.04.4 LTS system (with all apt updates applied and the latest 470.86 proprietary Nvidia driver version).

E.g. if I play a video file, I can watch the RSS gradually grow (in top or htop) as the frame count rises and then as it reaches around 4.7GiB it crashes.

No such issue is seen if I switch back to a 2.93 version of Blender and do exactly the same thing.

Exact steps for others to reproduce the error

For a given video and a freshly opened copy of Blender, the frame at which it crashes, on playback, is entirely consistent.

E.g. for the 4K Footage.mp4 file here (this is just footage that accompanied this Blender Daily video on YouTube), I can consistently play from frame 1 to frame 129 (using left-arrow to step frame-by-frame as I approach 129) and then Blender crashes as I step onto frame 130.

The frame I can reach varies depending on the file used, e.g. I can get much further in a typical 1080p file. But if I watch what's happening with htop then the failure always seems to occur as the RSS goes just a little above 4700MiB.

E.g. here you can see that Blender's RSS is 580MiB before I started playback:

By frame 129, RSS has grown to 4703MiB:

Stepping onto the next frame caused it to crash (and it consistently crashes on just that frame). As you can see from the screenshots, the system has plenty of free memory and is not heavily loaded.

If I run Blender with strace then the last few lines I see are:

read(28, "\301i2\325\251\263xu\215\267\206Y\357\207\324\301\4.\347\207M\333\332(RR\207\353\331NT\242"..., 32768) = 32768
futex(0x7f578aed7a04, FUTEX_WAKE_PRIVATE, 1) = 1
madvise(0x7f5766c0a000, 33558528, MADV_DONTNEED) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x10} ---
write(1, "Writing: /tmp/blender.crash.txt\n", 32Writing: /tmp/blender.crash.txt
) = 32

The full strace output is here:

The blender.crash.txt is here:

Exact steps:

• Start Blender and select VFX.
• In the middle Movie Clip editor (the one with mode Tracking and view Clip), click Open and select a downloaded copy of the Footage.mp4 file linked to above.
• Press Space to start playback and then, as the frame count nears 129, pause and start to step forward one frame at a time with cursor left-arrow.
• Everything should go fine up to including frame 129 but on stepping onto frame 130 Blender crashes.

I can reproduce this with any reasonably long video clip - the frame at which Blender crashes depends on the video (4K videos blow up much earlier than 1080p videos) but the frame at which it crashes is consistent for any given video, i.e. I can get it to crash repeatedly at exactly the same point.