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Linux 5.12-rc2

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Linux

Ok, so this is a couple of days early, but rc1 had the nasty swapfile
issue, so I'm just accelerating rc2 a bit.

Outside of the swapfile IO offset fix, the only other thing that
stands out is some io_uring thread handling re-organization, which not
only solved a few fundamental issues, but actually made the code
smaller and simpler too.

Other than that it all looks pretty normal: drivers dominate (with
sound being most notable, with the ASoC Intel SOF support being split
up sanely). But there's some btrfs work, kvm, iscsi, etc. A few random
things all over.

Shortlog appended for your viewing pleasure, and I sincerely hope (and
believe) that rc2 is in a lot better shape than rc1 was.

              Linus

Read more

Also: Linux 5.12-rc2 Released Early - A Rare Friday Kernel Due To That Nasty Corruption Issue

Radeon RX 6800 Series Seeing Some Small Gains With Linux 5.12 - Phoronix

Kernel prepatch 5.12-rc2

  • Kernel prepatch 5.12-rc2

    Linus has released 5.12-rc2 a little sooner than would normally be expected due to the problems with 5.12-rc1. "Other than that it all looks pretty normal".

Tabloids personify Linux news

  • Linus Torvalds pushes out emergency Linux update

    In a break from tradition, Linux kernel head honcho Linus Torvalds has published the newest release earlier than usual to address a filesystem corruption issue in the previous release.

    Torvalds noted that last week’s v5.12-rc1 broke the swapfile in an unusual way that could trash the entire filesystem on certain installations. Before he put out the update to correct that issue, Torvalds marked the previous release as v5.12-rc1-dontuse to ward off anyone from using that particular release in their Linux machines.

    “Ok, so this is a couple of days early, but rc1 had the nasty swapfile issue, so I'm just accelerating rc2 a bit,” noted Torvalds as he merged the fix that was released in the days following the rc1 release.

  • Linus Torvalds issues early Linux Kernel update to fix swapfile SNAFU

    Linux overlord Linus Torvalds has rushed out a new release candidate of Linux 5.12 after the first in the new series was found to include a ‘subtle and very nasty bug’ that was so serious he marked rc1 as unsuitable for use.

    “We had a very innocuous code cleanup and simplification that raised no red flags at all, but had a subtle and very nasty bug in it: swap files stopped working right. And they stopped working in a particularly bad way: the offset of the start of the swap file was lost,” Torvalds wrote in a March 3rd post to the Linux Kernel Mailing List.

    “Swapping still happened, but it happened to the wrong part of the filesystem, with the obvious catastrophic end results.”

    So catastrophic that, as Torvalds explained, “you can end up with a filesystem that is essentially overwritten by random swap data.”

  • Linus Torvalds warns: Watch out for this unusually nasty bug in Linux 5.12 rc1

    Linus Torvalds has issued a warning to open-source developers to avoid the first release candidate (RC) of the Linux kernel 5.12.

    Linux kernel 5.12 was released on time despite the snow storms that lashed Oregon and knocked out power to Torvalds' home for the better part of a week. Torvalds and his thousands of contributors managed to get version 5.12 out on time, but he now says RC 5.12 is a "double ungood" that can have catastrophic consequences for a computer's filesystem.

ZDNet says behind the news

  • Linus Torvalds fixes 'double ungood' Linux kernel bug

    It wasn't an ordinary week at Linux creator's Linus Torvalds house in Portland, OR. A snowstorm had knocked out power to Torvalds' home for the better part of a week. Despite that, Torvalds still got the first release candidate of the latest Linux kernel 5.12 out the door. That turned out to be a real mistake. The release, which was meant only for people who are testing the Linux kernel for bugs, turned out to have a bug for the ages, which would wreck test systems. Now it's been fixed.

    [...]

    This blunder, Torvalds said, started with "a very innocuous code cleanup and simplification that raised no red flags at all, but [it] had a subtle and very nasty bug in it: Swap files stopped working right. And they stopped working in a particularly bad way: the offset of the start of the swap file was lost. Swapping still happened, but it happened to the wrong part of the filesystem, with the obvious catastrophic end results."

    Whoops!

    In other words, when you'd run the release candidate code and you ran out of memory, your computer would do what it was supposed to do and write idle data and programs to the swap file. So far, so good. That happens on busy Linux systems every second of the day. Here, though, instead of being written safely to the swap file, data was written on top of your existing files. Thus, with this bug, your computer could shortly come to a complete and utter stop.

    Or, as Torvalds put it, "you can end up with a filesystem that is essentially overwritten by random swap data. This is what we in the industry call 'double ungood.'" That's for sure!

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