The generic open callback for the mem class devices is "protected" by
the bkl.
Let's look at the datas manipulated inside memory_open:
- inode and file: safe
- the devlist: safe because it is constant
- the memdev classes inside this array are safe too (constant)
After we find out which memdev file operation we need to use, we call
its open callback. Depending on the targeted memdev, we call either
open_port() that doesn't manipulate any racy data (just a capable()
check), or we call nothing.
So it's safe to remove the big kernel lock there.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1255113062-5835-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* mark struct vm_area_struct::vm_ops as const
* mark vm_ops in AGP code
But leave TTM code alone, something is fishy there with global vm_ops
being used.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In read_zero, we check for access_ok() once for the count bytes. It is
unnecessarily checked again in clear_user. Use __clear_user, which does
not check for access_ok().
Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This allows subsytems to provide devtmpfs with non-default permissions
for the device node. Instead of the default mode of 0600, null, zero,
random, urandom, full, tty, ptmx now have a mode of 0666, which allows
non-privileged processes to access standard device nodes in case no
other userspace process applies the expected permissions.
This also fixes a wrong assignment in pktcdvd and a checkpatch.pl complain.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
When I build and boot -next on fedora 10, I can not login anymore.
When I input the user name and password, the system does not output
any message and requires user to input the user name and password
again and again.
I find the patch which caused this problem with "GIT BISECT" command.
And the patch is
commit 7c4b7daa1878972ed0137c95f23569124bd6e2b1
"mem_class: use minor as index instead of searching the array".
Though I don't know the real reason why user could not login, I
confirmed the patch I made as following could resolve the problem on
fedora 10.
Signed-off-by: Jin Dongming <jin.dongming@np.css.fujitsu.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Declare the device list with the minor numbers as the index, which saves us from
searching for a matching list entry. Remove old devfs permissions declaration.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This enables us to track who does what and print info. Its main use
is catching dirty inodes on the default_backing_dev_info, so we can
fix that up.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
memory_open() ignores devlist and does a switch for each item, duplicating
code and conditional definitions.
Clean it up by adding backing_dev_info to devlist and use it to lookup for
the minor device.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Adriano dos Santos Fernandes <adrianosf@uol.com.br>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This helps with bad latencies for large reads from /dev/zero, but might
conceivably break some application that "knows" that a read of /dev/zero
cannot return early. So do this early in the merge window to give us
maximal test coverage, even if the patch is totally trivial.
Obviously, no well-behaved application should ever depend on the read
being uninterruptible, but hey, bugs happen.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While running 20 parallel instances of dd as follows:
#!/bin/bash
for i in `seq 1 20`; do
dd if=/dev/zero of=/export/hda3/dd_$i bs=1073741824 count=1 &
done
wait
on a 16G machine, we noticed that rather than just killing the processes,
the entire kernel went down. Stracing dd reveals that it first does an
mmap2, which makes 1GB worth of zero page mappings. Then it performs a
read on those pages from /dev/zero, and finally it performs a write.
The machine died during the reads. Looking at the code, it was noticed
that /dev/zero's read operation had been changed by
557ed1fa26 ("remove ZERO_PAGE") from giving
zero page mappings to actually zeroing the page.
The zeroing of the pages causes physical pages to be allocated to the
process. But, when the process exhausts all the memory that it can, the
kernel cannot kill it, as it is still in the kernel mode allocating more
memory. Consequently, the kernel eventually crashes.
To fix this, I propose that when a fatal signal is pending during
/dev/zero read operation, we simply return and let the user process die.
Signed-off-by: Salman Qazi <sqazi@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Modified error return and comment trivially. - Linus]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/dev/mem mmap code was doing memtype reserve/free for a while now.
Recently we added memtype tracking in remap_pfn_range, and /dev/mem mmap
uses it indirectly. So, we don't need seperate tracking in /dev/mem code
any more. That means another ~100 lines of code removed :-).
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <20090409212709.085210000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Sparse output following warnings.
mm/vmalloc.c:1436:6: warning: symbol 'vread' was not declared. Should it be static?
mm/vmalloc.c:1474:6: warning: symbol 'vwrite' was not declared. Should it be static?
However, it is used by /dev/kmem. fixed here.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use generic_access_phys as the access_process_vm access function for
/dev/mem mappings. This makes it possible to debug the X server.
[akpm@linux-foundation.org: repair all the architectures which broke]
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Benjamin Herrensmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
device_create() is race-prone, so use the race-free
device_create_drvdata() instead as device_create() is going away.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
From: Arjan van de Ven <arjan@infradead.org>
Date: Sat, 19 Jul 2008 15:47:17 -0700
CONFIG_NONPROMISC_DEVMEM was a rather confusing name - but renaming it
to CONFIG_PROMISC_DEVMEM causes problems on architectures that do not
support this feature; this patch renames it to CONFIG_STRICT_DEVMEM,
so that architectures can opt-in into it.
( the polarity of the option is still the same as it was originally; it
needs to be for now to not break architectures that don't have the
infastructure yet to support this feature)
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: "V.Radhakrishnan" <rk@atr-labs.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
Linus observed:
> The real bug is that we shouldn't have "double negatives", and
> certainly not negative config options. Making that "promiscuous
> /dev/mem" option a negated thing as a config option was bad.
right ... lets rename this option. There should never be a negation
in config options.
[ that reminds me of CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER, but that
is for another commit ;-) ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make /dev/kmem a config option; /dev/kmem is VERY rarely used, and when
used, it's generally for no good (rootkits tend to be the most common
users). With this config option, users have the choice to disable
/dev/kmem, saving some size as well.
A patch to disable /dev/kmem has been in the Fedora and RHEL kernels for
4+ years now without any known problems or legit users of /dev/kmem.
[akpm@linux-foundation.org: make CONFIG_DEVKMEM default to y]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use reserve_memtype and free_memtype wrappers for /dev/mem mmaps. The memtype
is slightly complicated here, given that we have to support existing X mappings.
We fallback on UC_MINUS for that.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Introduce phys_mem_access_prot_allowed(), which checks whether the mapping
is possible, without any conflicts and returns success or failure based on that.
phys_mem_access_prot() by itself does not allow failure case. This ability
to return error is needed for PAT where we may have aliasing conflicts.
x86 setup __HAVE_PHYS_MEM_ACCESS_PROT and move x86 specific code out of
/dev/mem into arch specific area.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add xlate and unxlate around /dev/mem read/write. This sets up the mapping
that can be used for /dev/mem read and write without aliasing worries.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Earlier patch that introduced CONFIG_NONPROMISC_DEVMEM, did the
range_is_allowed() check only for read and write. Add range_is_allowed()
check to mmap of /dev/mem as well.
Changes the paramaters of range_is_allowed() to pfn and size to handle
more than 32 bits of physical address on 32 bit arch cleanly.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch introduces a restriction on /dev/mem: Only non-memory can be
read or written unless the newly introduced config option is set.
The X server needs access to /dev/mem for the PCI space, but it doesn't need
access to memory; both the file permissions and SELinux permissions of /dev/mem
just make X effectively super-super powerful. With the exception of the
BIOS area, there's just no valid app that uses /dev/mem on actual memory.
Other popular users of /dev/mem are rootkits and the like.
(note: mmap access of memory via /dev/mem was already not allowed since
a really long time)
People who want to use /dev/mem for kernel debugging can enable the config
option.
The restrictions of this patch have been in the Fedora and RHEL kernels for
at least 4 years without any problems.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
André Goddard Rosa
Frederic Weisbecker
Alexey Dobriyan
Nikanth Karthikesan
Kay Sievers
Jin Dongming
Jens Axboe
Adriano dos Santos Fernandes
Linus Torvalds
Salman Qazi
Suresh Siddha
KOSAKI Motohiro
Greg Kroah-Hartman
Rik van Riel
Ingo Molnar
Jonathan Corbet
Arjan van de Ven
venkatesh.pallipadi@intel.com