Re: How best to bypass the page cache from within a kernel module?

[William Lee Irwin III <wli@holomorphy.com>]

On Wed, 17 Sep 2003, William Lee Irwin III wrote:
>> Well, you can get one from the slab allocator, though I expect there will
>> be a followup question here...

On Wed, Sep 17, 2003 at 05:30:50PM -0400, Alan Stern wrote:
> Yes :-)  The slab allocator will give me a nice piece of memory, but I 
> will still need to turn that into a valid mm_struct.  I can't call 
> alloc_mm() and friends because they're not EXPORTed.

Well, alloc_mm() doesn't really do much, so it should be easily
preppable along the same lines if it absolutely has to be a module. In
truth, the mm slab should be using a ctor (the vma slab too).


On Wed, 17 Sep 2003, William Lee Irwin III wrote:
>> Hmm. Sounds like you want to grab a user address space and do userspace
>> stuff inside there. Maybe avoid do_execve() etc. and call sys_*() for
>> everything else outright? The question itself probably wants sys_mmap()
>> or some such, or handle_mm_fault() depending on what you have in mind
>> for allocation.

On Wed, Sep 17, 2003 at 05:30:50PM -0400, Alan Stern wrote:
> sys_mmap() or something along those lines would be good.  But I can't call
> it directly because 2.6 doesn't EXPORT the sys_xxx functions.  Also, I'm
> not clear on whether mmap() lets you create an anonymous mapping -- one
> backed by swap space rather than a file -- that's what I would want to do.

That's a pain. It's probably easier to just compile the driver in, then.


On Wed, 17 Sep 2003, William Lee Irwin III wrote:
>> invalidate_inode_pages().

On Wed, Sep 17, 2003 at 05:30:50PM -0400, Alan Stern wrote:
> Great!  I'll search through the kernel code for it.

Should be in mm/filemap.c


-- wli
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