Fastmap kernel panic
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 28/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Quiet
- Tech stack
- c, debian, linux
- Domain
- operating-systems
Research direction
Start by reproducing the listed setup with commit 1af50c1, the dmap module loaded via modprobe, and scripts/load-it-blkdev.sh creating /dev/dmap/dmap1. Run rand_threads_read and rand_threads_write, then inspect the kernel panic details and the dmap-related entry points. Done means identifying the failure cause and documenting a fix or the additional information needed to diagnose it.
Written by the indexing model from the issue text.
Description
Hi,
I am trying to use Fastmap in combination with libvmmalloc or vmem to offload memory for quantum chemistry applications to many nvme-drives. I have gotten libvmmalloc and pmem to work. However, Fastmap gives me some trouble by causing kernel panics.
Could you please have a look an give or do you have any idea what the reason could be? Or which additional information would be helpful.
Steps to reproduce:
- Debian oldstable with Mainline Kernel 4.14.123 running in qemu 7.0.0
- fastmap commit 1af50c1
- swap off, transparent huge pages disabled
- modprobe dmap perma_mmap_buf_size=16
- /dev/dmap/dmap1 created using scripts/load-it-blkdev.sh
- rand_threads_read /dev/dmap/dmap1 2
- seems to work in the sense that is read from the device
- rand_threads_write /dev/dmap/dmap1 2
- starts to fill up the dram memory and finally leads to a kernel panic:
Things I have tried so far:
- reducing the size of the cache (perma_mmap_buf_size=16)
- Dominant language
- C
- Stars
- 37
- Forks
- 6
- PR merge metrics
- No merged PRs in 30d
Getting set up
This project ships no dev container, Dockerfile or contributing guide, so setting up is up to you: start from its README, and see our first-contribution guide for the general steps.
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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