Messages in this thread | | | Date | Tue, 26 Sep 2000 11:07:36 +0100 | From | "Stephen C. Tweedie" <> | Subject | Re: the new VMt |
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Hi,
On Mon, Sep 25, 2000 at 03:12:50PM -0600, yodaiken@fsmlabs.com wrote: > > > > > > I'm not too sure of what you have in mind, but if it is > > > "process creates vast virtual space to generate many page table > > > entries -- using mmap" > > > the answer is, virtual address space quotas and mmap should kill > > > the process on low mem for page tables. > > > > No. Page tables are not freed after munmap (and for good reason). The > > counting of page table "beans" is critical. > > I've seen the assertion before, reasons would be interesting.
Reason 1: under DoS attack, you want to target not the process using the most resources, but the *user* using the most resources (else a fork-bomb style attack can work around your OOM-killer algorithms).
Reason 2: if you've got tasks stuck in low-level page allocation routines, then you can't immediately kill -9 them, so reactive OOM killing always has vulnerabilities --- to be robust in preventing resource exhaustion you want limits on the use of those resources before they are exhausted --- the necessary accounting being part of what we refer to as "beancounter".
--Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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