Harry (Hyeonggon) Yoo
Posts
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107- Linux Kernel Developer @ Oracle (Linux Kernel MM) (2025.02 ~ Present)
- Reviewer for the Linux Slab subsystem
- Former Intern @ NVIDIA, SK Hynix, Panmnesia (Security, MM and CXL)
- B.Sc. in Computer Science & Engineering, Chungnam National University (Class of 2025)
Opinions are my own.
My interests are:
Memory Management,
Computer Architecture,
Circuit Design,
Virtualization
Harry (Hyeonggon) Yoo
hyeyoo
Edited 7 months ago
Reviewing what I learned about Linux context switching years ago because I forgot how it works.
A note for the next time I forget:
Context is switched from one kernel context to another. When a user process is going to be rescheduled, it first switches from user context to its kernel context after storing the registers on the kernel stack (pt_regs) due to a scheduler tick.
When switching between kernel contexts, only callee-saved registers are restored (from cpu_context in thread_struct), as the other registers should have been stored on the kernel stack (by the calling convention) before calling __switch_to()->cpu_switch_to() (on ARM64).
A note for the next time I forget:
Context is switched from one kernel context to another. When a user process is going to be rescheduled, it first switches from user context to its kernel context after storing the registers on the kernel stack (pt_regs) due to a scheduler tick.
When switching between kernel contexts, only callee-saved registers are restored (from cpu_context in thread_struct), as the other registers should have been stored on the kernel stack (by the calling convention) before calling __switch_to()->cpu_switch_to() (on ARM64).
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Harry (Hyeonggon) Yoo
hyeyoo
Edited 7 months ago
init_task is not the task_struct of the init process but of the swapper process.
It confuses me every time.
It confuses me every time.
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LWN.net is now @LWN@lwn.net
LWN@fosstodon.orgSeveral Russian developers lose kernel maintainership status
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@ljs @vbabka @lkundrak
It has gotten long as it has a bit of history :P
- Someone fixed a memory leak but introduced a double-free.
- Another person fixed the double-free, reintroducing the leak.
- A third person then fixed the leak, but reverted it after noticing it introduced another double-free.
It's been there because handling all error cases properly is complicated. Luckily, it's a kind of bug that someone is very unlikely to encounter, and it only leaks 32 bytes of memory.
It has gotten long as it has a bit of history :P
- Someone fixed a memory leak but introduced a double-free.
- Another person fixed the double-free, reintroducing the leak.
- A third person then fixed the leak, but reverted it after noticing it introduced another double-free.
It's been there because handling all error cases properly is complicated. Luckily, it's a kind of bug that someone is very unlikely to encounter, and it only leaks 32 bytes of memory.
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pope of nope 🇺🇦
lkundrak@metalhead.club
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Harry (Hyeonggon) Yoo
hyeyoo
Submitting my school assignment for “Contributing to Open Source Projects” class to linux-mm
https://lore.kernel.org/linux-mm/20241021091413.154775-1-42.hyeyoo@gmail.com/T
https://lore.kernel.org/linux-mm/20241021091413.154775-1-42.hyeyoo@gmail.com/T
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hyeyoo
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Harry (Hyeonggon) Yoo
hyeyoo
@lkundrak @vbabka
It reminds me of Vlasta's old LWN articles named "Patching until the COWs come home"
part 1 - https://lwn.net/Articles/849638/
part 2 - https://lwn.net/Articles/849876/
It reminds me of Vlasta's old LWN articles named "Patching until the COWs come home"
part 1 - https://lwn.net/Articles/849638/
part 2 - https://lwn.net/Articles/849876/
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Harry (Hyeonggon) Yoo
hyeyoo
I spent last week debugging why my machine was dead. The symptom was that it would turn off right away when it's turned on. I suspected the root cause was either the CPU, memory, motherboard, or power supply failing. So I replaced every component with parts from another computer, but it still didn't work.
The root cause was that the power button of the case was broken, causing it to always appear as if it was pressed, so it would turn off every time I turned it on. That was totally unexpected. I just replaced the power line with the reset line and it works fine now.
The root cause was that the power button of the case was broken, causing it to always appear as if it was pressed, so it would turn off every time I turned it on. That was totally unexpected. I just replaced the power line with the reset line and it works fine now.
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hyeyoo
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