Messages in this thread Patch in this message | | | Date | Wed, 26 Oct 2022 17:21:14 +0800 | Subject | Re: [PATCH] LoongArch: Fix memsection size | From | WANG Xuerui <> |
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On 2022/10/26 15:56, Jianmin Lv wrote: > On LoongArch, the physical address space ranging from 0 to 0xfffffff is > always memory, which is in the low half of the memsection range from 0 to > 0x1fffffff with 512M memsection size, and the high half will be a hole with > invalid memory pages.
The description is incorrect. For systems with less than 512MiB of memory for example, I believe not every address from 0x0 to 0x0fff_ffff is valid; and regarding the latter part of the sentence, what you mean by "invalid memory pages"...
> > This situation may cause some issues. For example, the range of 0x10000000 > to 0x1fffffff is io registers, which will be considered as valid memory range > since which is in the memsection of range of 0 to 0x1fffffff. During S3
... turns out to be totally valid, only of the I/O kind. (This might be a case of Chinglish that is actually conveying the incorrect meaning to unaware readers.)
> sleep and resume, these io registers will be saved and restored as valid memory > page (pfn_valid() of common version considers that all pages in a memsection > are valid), which will cause exception, especially when restoring during resume. > > We can use 256M size for memsection of LoongArch, or use the way as ARM64 to > walk through all memory memblock to check if a mem pfn is valid which maybe > lower performance. For simplicity, this patch just use the former way.
And the rest of the commit message is, unfortunately, a bit too verbose and hard to understand in general. I have to look at the actual change (luckily, a one-liner in this case) to confirm my understanding.
I think your intent is just to *avoid stepping into IO memory region during suspend/resume by reducing the section size order by one*. Try reducing the verbosity of the commit message in v2? I can't proofread and edit every commit due to limited time, so you have to practice and improve your writing skills after all. I'll review that piece of text afterwards. :)
> > Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn> > > diff --git a/arch/loongarch/include/asm/sparsemem.h b/arch/loongarch/include/asm/sparsemem.h > index 3d18cdf1b069..05903b40a625 100644 > --- a/arch/loongarch/include/asm/sparsemem.h > +++ b/arch/loongarch/include/asm/sparsemem.h > @@ -8,7 +8,7 @@ > * SECTION_SIZE_BITS 2^N: how big each section will be > * MAX_PHYSMEM_BITS 2^N: how much memory we can have in that space > */ > -#define SECTION_SIZE_BITS 29 /* 2^29 = Largest Huge Page Size */ > +#define SECTION_SIZE_BITS 28 > #define MAX_PHYSMEM_BITS 48 > > #endif /* CONFIG_SPARSEMEM */
The change is trivial indeed but I'm not immediately giving the R-b.
-- WANG "xen0n" Xuerui
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