linux/include
Atsushi Nemoto 77fff4ae2b [PATCH] Fix COW D-cache aliasing on fork
Problem:

1. There is a process containing two thread (T1 and T2).  The
   thread T1 calls fork().  Then dup_mmap() function called on T1 context.

static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
	...
	flush_cache_mm(current->mm);
	...	/* A */
	(write-protect all Copy-On-Write pages)
	...	/* B */
	flush_tlb_mm(current->mm);
	...

2. When preemption happens between A and B (or on SMP kernel), the
   thread T2 can run and modify data on COW pages without page fault
   (modified data will stay in cache).

3. Some time after fork() completed, the thread T2 may cause a page
   fault by write-protect on a COW page.

4. Then data of the COW page will be copied to newly allocated
   physical page (copy_cow_page()).  It reads data via kernel mapping.
   The kernel mapping can have different 'color' with user space
   mapping of the thread T2 (dcache aliasing).  Therefore
   copy_cow_page() will copy stale data.  Then the modified data in
   cache will be lost.

In order to allow architecture code to deal with this problem allow
architecture code to override copy_user_highpage() by defining
__HAVE_ARCH_COPY_USER_HIGHPAGE in <asm/page.h>.

The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 09:27:07 -08:00
..
acpi
asm-alpha
asm-arm [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-arm26
asm-avr32 [PATCH] getting rid of all casts of k[cmz]alloc() calls 2006-12-13 09:05:58 -08:00
asm-cris
asm-frv [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-generic Make sure we populate the initroot filesystem late enough 2006-12-11 12:12:04 -08:00
asm-h8300
asm-i386 [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-ia64 [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-m32r
asm-m68k [PATCH] remove the broken BLK_DEV_SWIM_IOP driver 2006-12-13 09:05:53 -08:00
asm-m68knommu
asm-mips [MIPS] IP27: Don't drag <asm/sn/arch.h> into topology.h. 2006-12-12 01:46:24 +00:00
asm-parisc
asm-powerpc [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-ppc Merge branch 'for_paulus' of master.kernel.org:/pub/scm/linux/kernel/git/galak/powerpc 2006-12-11 16:31:42 +11:00
asm-s390
asm-sh [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-sh64 [PATCH] getting rid of all casts of k[cmz]alloc() calls 2006-12-13 09:05:58 -08:00
asm-sparc
asm-sparc64
asm-um
asm-v850
asm-x86_64 [PATCH] PM: Fix SMP races in the freezer 2006-12-13 09:05:49 -08:00
asm-xtensa [PATCH] Xtensa: Add ktermios and minor filename fix 2006-12-13 09:05:50 -08:00
crypto
keys
linux [PATCH] Fix COW D-cache aliasing on fork 2006-12-13 09:27:07 -08:00
math-emu
media
mtd
net [PATCH] hci endianness annotations 2006-12-13 09:05:52 -08:00
pcmcia
rdma IB: Add DMA mapping functions to allow device drivers to interpose 2006-12-12 14:27:41 -08:00
rxrpc
scsi
sound
video [PATCH] sstfb: add sysfs interface 2006-12-13 09:05:55 -08:00
Kbuild