Messages in this thread | | | Date | Mon, 9 Mar 2020 15:59:45 +0000 | From | Catalin Marinas <> | Subject | Re: [PATCH] vfs: keep inodes with page cache off the inode shrinker LRU |
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On Sun, Mar 08, 2020 at 11:58:52AM +0100, Arnd Bergmann wrote: > - revisit CONFIG_VMSPLIT_4G_4G for arm32 (and maybe mips32) > to see if it can be done, and what the overhead is. This is probably > more work than the others combined, but also the most promising > as it allows the most user address space and physical ram to be used.
A rough outline of such support (and likely to miss some corner cases):
1. Kernel runs with its own ASID and non-global page tables.
2. Trampoline code on exception entry/exit to handle the TTBR0 switching between user and kernel.
3. uaccess routines need to be reworked to pin the user pages in memory (get_user_pages()) and access them via the kernel address space.
Point 3 is probably the ugliest and it would introduce a noticeable slowdown in certain syscalls.
-- Catalin
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