From: Andrew Morton <akpm@osdl.org> To: Andrea Arcangeli <andrea@novell.com> Cc: shaggy@austin.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] zap_pte_range should not mark non-uptodate pages dirty Date: Thu, 21 Oct 2004 16:02:33 -0700 [thread overview] Message-ID: <20041021160233.68a84971.akpm@osdl.org> (raw) In-Reply-To: <20041021223613.GA8756@dualathlon.random> Andrea Arcangeli <andrea@novell.com> wrote: > > On Thu, Oct 21, 2004 at 02:45:31PM -0700, Andrew Morton wrote: > > Maybe we should revisit invalidate_inode_pages2(). It used to be an > > invariant that "pages which are mapped into process address space are > > always uptodate". We broke that (good) invariant and we're now seeing > > some fallout. There may be more. > > such invariant doesn't exists since 2.4.10. There's no way to get mmaps > reload data from disk without breaking such an invariant. There are at least two ways: a) Set a new page flag in invalidate, test+clear that at fault time b) shoot down all pte's mapping the locked page at invalidate time, mark the page not uptodate. The latter is complex but has the advantage of fixing the current half-assed situation wherein existing mmaps are seeing invalidated data. > It's not even > for the write side, it's buffered read against O_DIRECT write that > requires breaking such invariant. > > Either you fix it the above way, or you remove the BUG() in pdflush and > you simply clear the dirty bit without doing anything, both are fine, > peraphs we should do both, but the above is good to have anyways since > it's more efficient to not even show the not uptodate pages to pdflush. We could just remove the BUG in mpage_writepage() (which I assume is the one which was being hit) but we might still have a not uptodate page with uptodate buffers and I suspect that the kernel will either go BUG there instead or will bring the page uptodate again without performing any I/O. But I haven't checked that.
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@osdl.org> To: Andrea Arcangeli <andrea@novell.com> Cc: shaggy@austin.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] zap_pte_range should not mark non-uptodate pages dirty Date: Thu, 21 Oct 2004 16:02:33 -0700 [thread overview] Message-ID: <20041021160233.68a84971.akpm@osdl.org> (raw) In-Reply-To: <20041021223613.GA8756@dualathlon.random> Andrea Arcangeli <andrea@novell.com> wrote: > > On Thu, Oct 21, 2004 at 02:45:31PM -0700, Andrew Morton wrote: > > Maybe we should revisit invalidate_inode_pages2(). It used to be an > > invariant that "pages which are mapped into process address space are > > always uptodate". We broke that (good) invariant and we're now seeing > > some fallout. There may be more. > > such invariant doesn't exists since 2.4.10. There's no way to get mmaps > reload data from disk without breaking such an invariant. There are at least two ways: a) Set a new page flag in invalidate, test+clear that at fault time b) shoot down all pte's mapping the locked page at invalidate time, mark the page not uptodate. The latter is complex but has the advantage of fixing the current half-assed situation wherein existing mmaps are seeing invalidated data. > It's not even > for the write side, it's buffered read against O_DIRECT write that > requires breaking such invariant. > > Either you fix it the above way, or you remove the BUG() in pdflush and > you simply clear the dirty bit without doing anything, both are fine, > peraphs we should do both, but the above is good to have anyways since > it's more efficient to not even show the not uptodate pages to pdflush. We could just remove the BUG in mpage_writepage() (which I assume is the one which was being hit) but we might still have a not uptodate page with uptodate buffers and I suspect that the kernel will either go BUG there instead or will bring the page uptodate again without performing any I/O. But I haven't checked that. -- 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>
next prev parent reply other threads:[~2004-10-21 23:11 UTC|newest] Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-10-21 21:15 [PATCH] zap_pte_range should not mark non-uptodate pages dirty Dave Kleikamp 2004-10-21 21:15 ` Dave Kleikamp 2004-10-21 21:45 ` Andrew Morton 2004-10-21 21:45 ` Andrew Morton 2004-10-21 22:36 ` Andrea Arcangeli 2004-10-21 22:36 ` Andrea Arcangeli 2004-10-21 23:02 ` Andrew Morton [this message] 2004-10-21 23:02 ` Andrew Morton 2004-10-21 23:20 ` Andrea Arcangeli 2004-10-21 23:20 ` Andrea Arcangeli 2004-10-21 23:42 ` Andrew Morton 2004-10-21 23:42 ` Andrew Morton 2004-10-22 0:15 ` Andrew Morton 2004-10-22 0:15 ` Andrew Morton 2004-10-22 0:41 ` Andrea Arcangeli 2004-10-22 0:41 ` Andrea Arcangeli 2004-10-22 2:51 ` Rik van Riel 2004-10-22 2:51 ` Rik van Riel 2004-10-22 16:19 ` Andrea Arcangeli 2004-10-22 16:19 ` Andrea Arcangeli 2004-10-22 0:30 ` Andrea Arcangeli 2004-10-22 0:30 ` Andrea Arcangeli 2004-10-22 1:22 ` Andrea Arcangeli 2004-10-22 1:22 ` Andrea Arcangeli 2004-10-22 2:03 ` Andrew Morton 2004-10-22 2:03 ` Andrew Morton 2004-10-22 16:17 ` Andrea Arcangeli 2004-10-22 16:17 ` Andrea Arcangeli 2004-10-22 17:04 ` Andrea Arcangeli 2004-10-22 17:04 ` Andrea Arcangeli 2004-10-22 23:24 ` Andrew Morton 2004-10-22 23:24 ` Andrew Morton 2004-10-25 13:58 ` Dave Kleikamp 2004-10-25 13:58 ` Dave Kleikamp 2004-10-26 0:35 ` Andrea Arcangeli 2004-10-26 0:35 ` Andrea Arcangeli 2004-11-09 14:15 ` Dave Kleikamp 2004-11-09 14:15 ` Dave Kleikamp 2004-11-09 14:46 ` Andrea Arcangeli 2004-11-09 14:46 ` Andrea Arcangeli 2004-11-09 19:51 ` Andrew Morton 2004-11-09 19:51 ` Andrew Morton 2004-11-09 19:46 ` Andrew Morton 2004-11-09 19:46 ` Andrew Morton
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20041021160233.68a84971.akpm@osdl.org \ --to=akpm@osdl.org \ --cc=andrea@novell.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=shaggy@austin.ibm.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.