William Lee Irwin III wrote:

On Sat, Dec 18, 2004 at 05:57:12PM +1100, Nick Piggin wrote:

quoted

Rename clear_page_tables to clear_page_range. clear_page_range takes byte
ranges, and aggressively frees page table pages. Maybe useful to control
page table memory consumption on 4-level architectures (and even 3 level
ones).
Possible downsides are:
- flush_tlb_pgtables gets called more often (only a problem for sparc64
 AFAIKS).
- the opportunistic "expand to fill PGDIR_SIZE hole" logic that ensures
 something actually gets done under the old system is still in place.
 This could sometimes make unmapping small regions more inefficient. There
 are some other solutions to look at if this is the case though.
Signed-off-by: Nick Piggin <redacted>

I wrote something equivalent to this in September, but dropped it on the
floor after some private replies etc. indicated no one gave a damn about
the testcase I posted in Message-ID: [off-list ref]
where the pagetable leak fooled the OOM killer into shooting the wrong
processes long enough to trigger a panic() in oom_kill.c

Hmm... I actually didn't see your post, but it seems like something
worth pursuing.

My incling is that the hybrid expand-to-hole / refcounting approach
I outlined earlier in the thread might be the way to go.

I'll be interested to hear what the powers that be think.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"aart@kvack.org"> aart@kvack.org </a>