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A deep dive into Debian 13 /tmp: What's new, and what to do if you don't like it

(lowendbox.com)
150 points shaunpud | 1 comments | 29 Aug 25 02:39 UTC | HN request time: 0.201s | source
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nrdvana ◴[29 Aug 25 04:29 UTC] No.45060203[source]▶
The third mitigating feature the article forgot to mention is that tmpfs can get paged out to the swap partition. If you drop a large file there and forget it, it will all end up in the swap partition if applications are demanding more memory.
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m463 ◴[29 Aug 25 06:10 UTC] No.45060756[source]▶
what swap partition?

I meant this sort of jokingly. I think have a few linux systems that were never configured with swap partitions or swapfiles.

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edoceo ◴[29 Aug 25 06:17 UTC] No.45060793[source]▶
I'm with you. I don't swap. Processes die. OOM. Linux can recover and not lose data. Just unavailable for a moment.
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Balinares ◴[29 Aug 25 06:40 UTC] No.45060941[source]▶
Swapping still occurs regardless. If there is no swap space the kernel swaps out code pages instead. So, running programs. The code pages then need to be loaded again from disk when the corresponding process is next scheduled and needs them.

This is not very efficient and is why a bit of actual swap space is generally recommended.

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1. adrian_b ◴[29 Aug 25 10:38 UTC] No.45062376[source]▶
Unlike swapping, freeing code pages does no writing to HDD/SSD, but it only needs to reload the pages when they are needed again in the future, therefore it is more efficient than swapping.

I have stopped using swapping on all my Linux servers, desktops and laptops more than 20 years ago. At that time it was a great improvement and since then it has never caused any problems. However, I have been generous with the amount of RAM I install, for any computer having at least the NUC size there are many years since I have never used less than 32 GB, while for new computers I do not intend to use less than 64 GB.

With recent enough Linux kernels, using tmpfs for /tmp is perfectly fine. Nevertheless, for decades using tmpfs for /tmp had been dangerous, because copying a file through /tmp would lose metadata, e.g. by truncating file timestamps and by stripping the extended file attributes.

Copying files through /tmp was frequent between the users of multi-user computers where there was no other directory where all users had write access and the former behavior of Linux tmpfs was very surprising for them.