From: Manfred Spraul <manfreds@colorfullife.com>
To: Kanoj Sarcar <kanoj@google.engr.sgi.com>
Cc: torvalds@transmeta.com, sct@redhat.com, andrea@suse.de,
viro@math.psu.edu, linux-mm@kvack.org,
linux-kernel@vger.rutgers.edu
Subject: Re: [PATCH] kanoj-mm17-2.3.21 kswapd vma scanning protection
Date: Fri, 15 Oct 1999 22:47:37 +0200 [thread overview]
Message-ID: <380792E9.7D1E5E1@colorfullife.com> (raw)
In-Reply-To: <199910151843.LAA14256@google.engr.sgi.com>
Kanoj Sarcar wrote:
> Explain ... who are the readers, and who are the writers? I think if you
> are talking about a semaphore lock being held thru out swapout() in the
> try_to_swap_out path, you are reduced to the same deadlock I just pointed
> out. I was talking more about a monitor like approach here.
The lock is held thru out swapout(), but it is a shared lock: multiple
swapper threads can own it. There should be no lock-up.
reader: swapper. Reentrancy is not a problem because it is a read-lock,
ie shared. The implementation must starve exclusive waiters (ie a reader
is allowed to continue even if a writer is waiting).
write: everyone who changes the vma list. These functions must not sleep
while owning the ERESOURCE (IIRC the NT kernel name) exclusive.
I hope I have not overlocked a detail,
Manfred
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next prev parent reply other threads:[~1999-10-15 20:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-10-15 0:06 Kanoj Sarcar
1999-10-15 11:58 ` Manfred Spraul
1999-10-15 16:38 ` Kanoj Sarcar
1999-10-15 18:26 ` Manfred Spraul
1999-10-15 18:43 ` Kanoj Sarcar
1999-10-15 20:47 ` Manfred Spraul [this message]
1999-10-15 21:13 ` Kanoj Sarcar
1999-10-15 21:24 ` Linus Torvalds
1999-10-15 21:39 ` Kanoj Sarcar
1999-10-15 22:04 ` Linus Torvalds
1999-10-15 22:32 ` Kanoj Sarcar
1999-10-15 23:16 ` Manfred Spraul
1999-10-16 0:44 ` Linus Torvalds
1999-10-18 19:45 ` Kanoj Sarcar
1999-10-18 20:02 ` Linus Torvalds
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