From: Nick Piggin <npiggin@suse.de>
To: Linux Memory Management <linux-mm@kvack.org>
Cc: Neil Brown <neilb@suse.de>, Andrew Morton <akpm@osdl.org>,
Anton Altaparmakov <aia21@cam.ac.uk>,
Chris Mason <chris.mason@oracle.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>
Subject: [patch 5/6] mm: debug write deadlocks
Date: Fri, 13 Oct 2006 18:44:42 +0200 (CEST) [thread overview]
Message-ID: <20061013143606.15438.18462.sendpatchset@linux.site> (raw)
In-Reply-To: <20061013143516.15438.8802.sendpatchset@linux.site>
Allow CONFIG_DEBUG_VM to switch off the prefaulting logic, to simulate the
difficult race where the page may be unmapped before calling copy_from_user.
Makes the race much easier to hit.
This probably needn't go upstream.
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1895,6 +1895,7 @@ generic_file_buffered_write(struct kiocb
if (maxlen > bytes)
maxlen = bytes;
+#ifndef CONFIG_DEBUG_VM
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
@@ -1902,6 +1903,7 @@ generic_file_buffered_write(struct kiocb
* up-to-date.
*/
fault_in_pages_readable(buf, maxlen);
+#endif
page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
if (!page) {
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@suse.de>
To: Linux Memory Management <linux-mm@kvack.org>
Cc: Neil Brown <neilb@suse.de>, Andrew Morton <akpm@osdl.org>,
Anton Altaparmakov <aia21@cam.ac.uk>,
Chris Mason <chris.mason@oracle.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>
Subject: [patch 5/6] mm: debug write deadlocks
Date: Fri, 13 Oct 2006 18:44:42 +0200 (CEST) [thread overview]
Message-ID: <20061013143606.15438.18462.sendpatchset@linux.site> (raw)
In-Reply-To: <20061013143516.15438.8802.sendpatchset@linux.site>
Allow CONFIG_DEBUG_VM to switch off the prefaulting logic, to simulate the
difficult race where the page may be unmapped before calling copy_from_user.
Makes the race much easier to hit.
This probably needn't go upstream.
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1895,6 +1895,7 @@ generic_file_buffered_write(struct kiocb
if (maxlen > bytes)
maxlen = bytes;
+#ifndef CONFIG_DEBUG_VM
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
@@ -1902,6 +1903,7 @@ generic_file_buffered_write(struct kiocb
* up-to-date.
*/
fault_in_pages_readable(buf, maxlen);
+#endif
page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
if (!page) {
--
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next prev parent reply other threads:[~2006-10-13 16:44 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-13 16:43 [rfc] buffered write deadlock fix Nick Piggin
2006-10-13 16:43 ` Nick Piggin
2006-10-13 16:44 ` [patch 1/6] mm: revert "generic_file_buffered_write(): handle zero length iovec segments" Nick Piggin
2006-10-13 16:44 ` Nick Piggin, Andrew Morton
2006-10-13 16:44 ` [patch 2/6] mm: revert "generic_file_buffered_write(): deadlock on vectored write" Nick Piggin
2006-10-13 16:44 ` Nick Piggin, Andrew Morton
2006-10-13 16:44 ` [patch 3/6] mm: generic_file_buffered_write cleanup Nick Piggin
2006-10-13 16:44 ` Nick Piggin, Andrew Morton
2006-10-13 16:44 ` [patch 4/6] mm: comment mmap_sem / lock_page lockorder Nick Piggin
2006-10-13 16:44 ` Nick Piggin
2006-10-13 16:44 ` Nick Piggin [this message]
2006-10-13 16:44 ` [patch 5/6] mm: debug write deadlocks Nick Piggin
2006-10-13 16:44 ` [patch 6/6] mm: fix pagecache " Nick Piggin
2006-10-13 16:44 ` Nick Piggin, Andrew Morton
2006-10-13 22:14 ` Andrew Morton
2006-10-13 22:14 ` Andrew Morton
2006-10-14 4:19 ` Nick Piggin
2006-10-14 4:19 ` Nick Piggin
2006-10-14 4:30 ` Nick Piggin
2006-10-14 4:30 ` Nick Piggin
2006-10-15 11:35 ` Peter Zijlstra
2006-10-15 11:35 ` Peter Zijlstra
2006-10-14 5:04 ` Nick Piggin
2006-10-14 5:04 ` Nick Piggin
2006-10-15 11:37 ` Peter Zijlstra
2006-10-15 11:37 ` Peter Zijlstra
2006-10-15 11:56 ` Nick Piggin
2006-10-15 11:56 ` Nick Piggin
2006-10-15 13:51 ` Peter Zijlstra
2006-10-15 13:51 ` Peter Zijlstra
2006-10-15 14:19 ` SPAM: " Nick Piggin
2006-10-15 14:19 ` Nick Piggin
2006-10-15 15:47 ` Peter Zijlstra
2006-10-15 15:47 ` Peter Zijlstra
2006-10-15 15:57 ` RRe: " Nick Piggin
2006-10-15 15:57 ` Nick Piggin
2006-10-15 16:13 ` Peter Zijlstra
2006-10-15 16:13 ` Peter Zijlstra
2006-10-16 15:24 ` pagefault_disable (was Re: [patch 6/6] mm: fix pagecache write deadlocks) Nick Piggin
2006-10-16 15:24 ` Nick Piggin
2006-10-16 16:05 ` Peter Zijlstra
2006-10-16 16:05 ` Peter Zijlstra
2006-10-16 16:12 ` Nick Piggin
2006-10-16 16:12 ` Nick Piggin
2006-10-18 14:25 ` [patch 6/6] mm: fix pagecache write deadlocks Chris Mason
2006-10-18 14:25 ` Chris Mason
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