From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 21 May 1999 10:25:42 -0400 (EDT) From: "Benjamin C.R. LaHaise" Subject: Re: Assumed Failure rates in Various o.s's ? In-Reply-To: <19990521120725.A581384@daimi.au.dk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Erik Corry Cc: Kanoj Sarcar , ak-uu@muc.de, linux-mm@kvack.org List-ID: On Fri, 21 May 1999, Erik Corry wrote: > According to Andi you already fixed this with a read lock that > prevents mmap and mmunmap from doing anything while the copy > is running. This makes sense, since if you do it right with a > readers/writers lock you can keep out mmap without serialising > copy_to_user or copy_from_user. I really like the cleanliness of this approach, but it's troublesome: memory allocations in other threads would then get blocked during large IOs -- very bad. What if we instead move from the mm level semaphore to a per vma locking scheme? The mmap semaphore could become a spinlock for fudging with list of vmas, and mmap/page faults/... could lock the specific vma. Or would this be too heavy? -ben -- To unsubscribe, send a message with 'unsubscribe linux-mm my@address' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/