lkml.org 
[lkml]   [2020]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v2 1/3] mm/shuffle: don't move pages between zones and don't read garbage memmaps
    From
    Date
    > Hmm.. I thought this is the behavior for early section, while it looks current
    > code doesn't work like this:
    >
    > if (section_is_early && memmap)
    > free_map_bootmem(memmap);
    > else
    > depopulate_section_memmap(pfn, nr_pages, altmap);
    >
    > section_is_early is always "true" for early section, while memmap is not-NULL
    > only when sub-section map is empty.
    >
    > If my understanding is correct, when we remove a sub-section in early section,
    > the code would call depopulate_section_memmap(), which in turn free related
    > memmap. By removing the memmap, the return value from pfn_to_online_page() is
    > not a valid one.

    I think you're right, and pfn_valid() would also return true, as it is
    an early section. This looks broken.

    >
    > Maybe we want to write the code like this:
    >
    > if (section_is_early)
    > if (memmap)
    > free_map_bootmem(memmap);
    > else
    > depopulate_section_memmap(pfn, nr_pages, altmap);
    >

    I guess that should be the way to go

    @Dan, I think what Wei proposes here is correct, right? Or how does it
    work in the VMEMMAP case with early sections?

    --
    Thanks,

    David / dhildenb

    \
     
     \ /
      Last update: 2020-06-23 09:39    [W:4.376 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site