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2012-04-02module: Remove module size limitSasha Levin
commit f946eeb9313ff1470758e171a60fe7438a2ded3f upstream. Module size was limited to 64MB, this was legacy limitation due to vmalloc() which was removed a while ago. Limiting module size to 64MB is both pointless and affects real world use cases. Cc: Tim Abbott <tim.abbott@oracle.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02slub: Do not hold slub_lock when calling sysfs_slab_add()Christoph Lameter
commit 66c4c35c6bc5a1a452b024cf0364635b28fd94e4 upstream. sysfs_slab_add() calls various sysfs functions that actually may end up in userspace doing all sorts of things. Release the slub_lock after adding the kmem_cache structure to the list. At that point the address of the kmem_cache is not known so we are guaranteed exlusive access to the following modifications to the kmem_cache structure. If the sysfs_slab_add fails then reacquire the slub_lock to remove the kmem_cache structure from the list. Reported-by: Sasha Levin <levinsasha928@gmail.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02xfs: Fix oops on IO error during xlog_recover_process_iunlinks()Jan Kara
commit d97d32edcd732110758799ae60af725e5110b3dc upstream. When an IO error happens during inode deletion run from xlog_recover_process_iunlinks() filesystem gets shutdown. Thus any subsequent attempt to read buffers fails. Code in xlog_recover_process_iunlinks() does not count with the fact that read of a buffer which was read a while ago can really fail which results in the oops on agi = XFS_BUF_TO_AGI(agibp); Fix the problem by cleaning up the buffer handling in xlog_recover_process_iunlinks() as suggested by Dave Chinner. We release buffer lock but keep buffer reference to AG buffer. That is enough for buffer to stay pinned in memory and we don't have to call xfs_read_agi() all the time. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Ben Myers <bpm@sgi.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02backlight: fix typo in tosa_lcd.cMasanari Iida
commit 8da00edc1069f01c34510fa405dc15d96c090a3f upstream. Fix typo in drivers/video/backlight/tosa_lcd.c "tosa_lcd_reume" should be "tosa_lcd_resume". Signed-off-by: Masanari Iida <standby24x7@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02dm exception store: fix init error pathAndrei Warkentin
commit aadbe266f2f89ccc68b52f4effc7b3a8b29521ef upstream. Call the correct exit function on failure in dm_exception_store_init. Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02dm crypt: add missing error handlingMikulas Patocka
commit 72c6e7afc43e19f68a31dea204fc366624d6eee9 upstream. Always set io->error to -EIO when an error is detected in dm-crypt. There were cases where an error code would be set only if we finish processing the last sector. If there were other encryption operations in flight, the error would be ignored and bio would be returned with success as if no error happened. This bug is present in kcryptd_crypt_write_convert, kcryptd_crypt_read_convert and kcryptd_async_done. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02dm crypt: fix mempool deadlockMikulas Patocka
commit aeb2deae2660a1773c83d3c6e9e6575daa3855d6 upstream. This patch fixes a possible deadlock in dm-crypt's mempool use. Currently, dm-crypt reserves a mempool of MIN_BIO_PAGES reserved pages. It allocates first MIN_BIO_PAGES with non-failing allocation (the allocation cannot fail and waits until the mempool is refilled). Further pages are allocated with different gfp flags that allow failing. Because allocations may be done in parallel, this code can deadlock. Example: There are two processes, each tries to allocate MIN_BIO_PAGES and the processes run simultaneously. It may end up in a situation where each process allocates (MIN_BIO_PAGES / 2) pages. The mempool is exhausted. Each process waits for more pages to be freed to the mempool, which never happens. To avoid this deadlock scenario, this patch changes the code so that only the first page is allocated with non-failing gfp mask. Allocation of further pages may fail. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02udf: Fix deadlock in udf_release_file()Jan Kara
commit a0391a3ae91d301c0e59368531a4de5f0b122bcf upstream. udf_release_file() can be called from munmap() path with mmap_sem held. Thus we cannot take i_mutex there because that ranks above mmap_sem. Luckily, i_mutex is not needed in udf_release_file() anymore since protection by i_data_sem is enough to protect from races with write and truncate. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Reviewed-by: Namjae Jeon <linkinjeon@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02vfs: fix d_ancestor() case in d_materialize_uniqueMichel Lespinasse
commit b18dafc86bb879d2f38a1743985d7ceb283c2f4d upstream. In d_materialise_unique() there are 3 subcases to the 'aliased dentry' case; in two subcases the inode i_lock is properly released but this does not occur in the -ELOOP subcase. This seems to have been introduced by commit 1836750115f2 ("fix loop checks in d_materialise_unique()"). Signed-off-by: Michel Lespinasse <walken@google.com> [ Added a comment, and moved the unlock to where we generate the -ELOOP, which seems to be more natural. You probably can't actually trigger this without a buggy network file server - d_materialize_unique() is for finding aliases on non-local filesystems, and the d_ancestor() case is for a hardlinked directory loop. But we should be robust in the case of such buggy servers anyway. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02ext4: check for zero length extentTheodore Ts'o
commit 31d4f3a2f3c73f279ff96a7135d7202ef6833f12 upstream. Explicitly test for an extent whose length is zero, and flag that as a corrupted extent. This avoids a kernel BUG_ON assertion failure. Tested: Without this patch, the file system image found in tests/f_ext_zero_len/image.gz in the latest e2fsprogs sources causes a kernel panic. With this patch, an ext4 file system error is noted instead, and the file system is marked as being corrupted. https://bugzilla.kernel.org/show_bug.cgi?id=42859 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02ext4: ignore EXT4_INODE_JOURNAL_DATA flag with delallocLukas Czerner
commit 3d2b158262826e8b75bbbfb7b97010838dd92ac7 upstream. Ext4 does not support data journalling with delayed allocation enabled. We even do not allow to mount the file system with delayed allocation and data journalling enabled, however it can be set via FS_IOC_SETFLAGS so we can hit the inode with EXT4_INODE_JOURNAL_DATA set even on file system mounted with delayed allocation (default) and that's where problem arises. The easies way to reproduce this problem is with the following set of commands: mkfs.ext4 /dev/sdd mount /dev/sdd /mnt/test1 dd if=/dev/zero of=/mnt/test1/file bs=1M count=4 chattr +j /mnt/test1/file dd if=/dev/zero of=/mnt/test1/file bs=1M count=4 conv=notrunc chattr -j /mnt/test1/file Additionally it can be reproduced quite reliably with xfstests 272 and 269. In fact the above reproducer is a part of test 272. To fix this we should ignore the EXT4_INODE_JOURNAL_DATA inode flag if the file system is mounted with delayed allocation. This can be easily done by fixing ext4_should_*_data() functions do ignore data journal flag when delalloc is set (suggested by Ted). We also have to set the appropriate address space operations for the inode (again, ignoring data journal flag if delalloc enabled). Additionally this commit introduces ext4_inode_journal_mode() function because ext4_should_*_data() has already had a lot of common code and this change is putting it all into one function so it is easier to read. Successfully tested with xfstests in following configurations: delalloc + data=ordered delalloc + data=writeback data=journal nodelalloc + data=ordered nodelalloc + data=writeback nodelalloc + data=journal Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02jbd2: clear BH_Delay & BH_Unwritten in journal_unmap_bufferEric Sandeen
commit 15291164b22a357cb211b618adfef4fa82fc0de3 upstream. journal_unmap_buffer()'s zap_buffer: code clears a lot of buffer head state ala discard_buffer(), but does not touch _Delay or _Unwritten as discard_buffer() does. This can be problematic in some areas of the ext4 code which assume that if they have found a buffer marked unwritten or delay, then it's a live one. Perhaps those spots should check whether it is mapped as well, but if jbd2 is going to tear down a buffer, let's really tear it down completely. Without this I get some fsx failures on sub-page-block filesystems up until v3.2, at which point 4e96b2dbbf1d7e81f22047a50f862555a6cb87cb and 189e868fa8fdca702eb9db9d8afc46b5cb9144c9 make the failures go away, because buried within that large change is some more flag clearing. I still think it's worth doing in jbd2, since ->invalidatepage leads here directly, and it's the right place to clear away these flags. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02ext4: flush any pending end_io requests before DIO reads w/dioread_nolockJiaying Zhang
commit dccaf33fa37a1bc5d651baeb3bfeb6becb86597b upstream. (backported to 3.0 by mjt) There is a race between ext4 buffer write and direct_IO read with dioread_nolock mount option enabled. The problem is that we clear PageWriteback flag during end_io time but will do uninitialized-to-initialized extent conversion later with dioread_nolock. If an O_direct read request comes in during this period, ext4 will return zero instead of the recently written data. This patch checks whether there are any pending uninitialized-to-initialized extent conversion requests before doing O_direct read to close the race. Note that this is just a bandaid fix. The fundamental issue is that we clear PageWriteback flag before we really complete an IO, which is problem-prone. To fix the fundamental issue, we may need to implement an extent tree cache that we can use to look up pending to-be-converted extents. Signed-off-by: Jiaying Zhang <jiayingz@google.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02PM / Hibernate: Enable usermodehelpers in hibernate() error pathSrivatsa S. Bhat
commit 05b4877f6a4f1ba4952d1222213d262bf8c132b7 upstream. If create_basic_memory_bitmaps() fails, usermodehelpers are not re-enabled before returning. Fix this. And while at it, reword the goto labels so that they look more meaningful. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02e1000e: Avoid wrong check on TX hangJeff Kirsher
commit 09357b00255c233705b1cf6d76a8d147340545b8 upstream. Based on the original patch submitted my Michael Wang <wangyun@linux.vnet.ibm.com>. Descriptors may not be write-back while checking TX hang with flag FLAG2_DMA_BURST on. So when we detect hang, we just flush the descriptor and detect again for once. -v2 change 1 to true and 0 to false and remove extra () CC: Michael Wang <wangyun@linux.vnet.ibm.com> CC: Flavio Leitner <fbl@redhat.com> Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Tested-by: Aaron Brown <aaron.f.brown@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02pvrusb2: fix 7MHz & 8MHz DVB-T tuner support for HVR1900 rev D1F5Michael Krufky
commit 9ab2393fc3e460cd2040de1483918eb17abb822f upstream. The D1F5 revision of the WinTV HVR-1900 uses a tda18271c2 tuner instead of a tda18271c1 tuner as used in revision D1E9. To account for this, we must hardcode the frontend configuration to use the same IF frequency configuration for both revisions of the device. 6MHz DVB-T is unaffected by this issue, as the recommended IF Frequency configuration for 6MHz DVB-T is the same on both c1 and c2 revisions of the tda18271 tuner. Signed-off-by: Michael Krufky <mkrufky@linuxtv.org> Cc: Mike Isely <isely@pobox.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02lgdt330x: fix signedness error in i2c_read_demod_bytes()Xi Wang
commit 34817174fca0c5512c2d5b6ea0fc37a0337ce1d8 upstream. The error handling in lgdt3303_read_status() and lgdt330x_read_ucblocks() doesn't work, because i2c_read_demod_bytes() returns a u8 and (err < 0) is always false. err = i2c_read_demod_bytes(state, 0x58, buf, 1); if (err < 0) return err; Change the return type of i2c_read_demod_bytes() to int. Also change the return value on error to -EIO to make (err < 0) work. Signed-off-by: Xi Wang <xi.wang@gmail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02hwmon: (fam15h_power) Correct sign extension of running_avg_captureAndreas Herrmann
commit fc0900cbda9243957d812cd6b4cc87965f9fe75f upstream. Wrong bit was used for sign extension which caused wrong end results. Thanks to Andre for spotting this bug. Reported-by: Andre Przywara <andre.przywara@amd.com> Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02proc-ns: use d_set_d_op() API to set dentry ops in proc_ns_instantiate().Pravin B Shelar
commit 1b26c9b334044cff6d1d2698f2be41bc7d9a0864 upstream. The namespace cleanup path leaks a dentry which holds a reference count on a network namespace. Keeping that network namespace from being freed when the last user goes away. Leaving things like vlan devices in the leaked network namespace. If you use ip netns add for much real work this problem becomes apparent pretty quickly. It light testing the problem hides because frequently you simply don't notice the leak. Use d_set_d_op() so that DCACHE_OP_* flags are set correctly. This issue exists back to 3.0. Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Reported-by: Justin Pettit <jpettit@nicira.com> Signed-off-by: Pravin B Shelar <pshelar@nicira.com> Signed-off-by: Jesse Gross <jesse@nicira.com> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02x86-32: Fix endless loop when processing signals for kernel tasksDmitry Adamushko
commit 29a2e2836ff9ea65a603c89df217f4198973a74f upstream. The problem occurs on !CONFIG_VM86 kernels [1] when a kernel-mode task returns from a system call with a pending signal. A real-life scenario is a child of 'khelper' returning from a failed kernel_execve() in ____call_usermodehelper() [ kernel/kmod.c ]. kernel_execve() fails due to a pending SIGKILL, which is the result of "kill -9 -1" (at least, busybox's init does it upon reboot). The loop is as follows: * syscall_exit_work: - work_pending: // start_of_the_loop - work_notify_sig: - do_notify_resume() - do_signal() - if (!user_mode(regs)) return; - resume_userspace // TIF_SIGPENDING is still set - work_pending // so we call work_pending => goto // start_of_the_loop More information can be found in another LKML thread: http://www.serverphorums.com/read.php?12,457826 [1] the problem was also seen on MIPS. Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Link: http://lkml.kernel.org/r/1332448765.2299.68.camel@dimm Cc: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@hack.frob.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02usbnet: don't clear urb->dev in tx_completetom.leiming@gmail.com
commit 5d5440a835710d09f0ef18da5000541ec98b537a upstream. URB unlinking is always racing with its completion and tx_complete may be called before or during running usb_unlink_urb, so tx_complete must not clear urb->dev since it will be used in unlink path, otherwise invalid memory accesses or usb device leak may be caused inside usb_unlink_urb. Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oliver@neukum.org> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02usbnet: increase URB reference count before usb_unlink_urbtom.leiming@gmail.com
commit 0956a8c20b23d429e79ff86d4325583fc06f9eb4 upstream. Commit 4231d47e6fe69f061f96c98c30eaf9fb4c14b96d(net/usbnet: avoid recursive locking in usbnet_stop()) fixes the recursive locking problem by releasing the skb queue lock, but it makes usb_unlink_urb racing with defer_bh, and the URB to being unlinked may be freed before or during calling usb_unlink_urb, so use-after-free problem may be triggerd inside usb_unlink_urb. The patch fixes the use-after-free problem by increasing URB reference count with skb queue lock held before calling usb_unlink_urb, so the URB won't be freed until return from usb_unlink_urb. Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oliver@neukum.org> Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02SUNRPC: We must not use list_for_each_entry_safe() in rpc_wake_up()Trond Myklebust
commit 540a0f7584169651f485e8ab67461fcb06934e38 upstream. The problem is that for the case of priority queues, we have to assume that __rpc_remove_wait_queue_priority will move new elements from the tk_wait.links lists into the queue->tasks[] list. We therefore cannot use list_for_each_entry_safe() on queue->tasks[], since that will skip these new tasks that __rpc_remove_wait_queue_priority is adding. Without this fix, rpc_wake_up and rpc_wake_up_status will both fail to wake up all functions on priority wait queues, which can result in some nasty hangs. Reported-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02UBI: fix eraseblock picking criteriaArtem Bityutskiy
commit 7eb3aa65853e1b223bfc786b023b702018cb76c0 upstream. The 'find_wl_entry()' function expects the maximum difference as the second argument, not the maximum absolute value. So the "unknown" eraseblock picking was incorrect, as Shmulik Ladkani spotted. This patch fixes the issue. Reported-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02UBI: fix error handling in ubi_scan()Richard Weinberger
commit a29852be492d61001d86c6ebf5fff9b93d7b4be9 upstream. Two bad things can happen in ubi_scan(): 1. If kmem_cache_create() fails we jump to out_si and call ubi_scan_destroy_si() which calls kmem_cache_destroy(). But si->scan_leb_slab is NULL. 2. If process_eb() fails we jump to out_vidh, call kmem_cache_destroy() and ubi_scan_destroy_si() which calls again kmem_cache_destroy(). Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02cifs: fix issue mounting of DFS ROOT when redirecting from one domain ↵Jeff Layton
controller to the next commit 1daaae8fa4afe3df78ca34e724ed7e8187e4eb32 upstream. This patch fixes an issue when cifs_mount receives a STATUS_BAD_NETWORK_NAME error during cifs_get_tcon but is able to continue after an DFS ROOT referral. In this case, the return code variable is not reset prior to trying to mount from the system referred to. Thus, is_path_accessible is not executed and the final DFS referral is not performed causing a mount error. Use case: In DNS, example.com resolves to the secondary AD server ad2.example.com Our primary domain controller is ad1.example.com and has a DFS redirection set up from \\ad1\share\Users to \\files\share\Users. Mounting \\example.com\share\Users fails. Regression introduced by commit 724d9f1. Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru Signed-off-by: Thomas Hadig <thomas@intapp.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02xfs: fix inode lookup raceDave Chinner
commit f30d500f809eca67a21704347ab14bb35877b5ee upstream. When we get concurrent lookups of the same inode that is not in the per-AG inode cache, there is a race condition that triggers warnings in unlock_new_inode() indicating that we are initialising an inode that isn't in a the correct state for a new inode. When we do an inode lookup via a file handle or a bulkstat, we don't serialise lookups at a higher level through the dentry cache (i.e. pathless lookup), and so we can get concurrent lookups of the same inode. The race condition is between the insertion of the inode into the cache in the case of a cache miss and a concurrently lookup: Thread 1 Thread 2 xfs_iget() xfs_iget_cache_miss() xfs_iread() lock radix tree radix_tree_insert() rcu_read_lock radix_tree_lookup lock inode flags XFS_INEW not set igrab() unlock inode flags rcu_read_unlock use uninitialised inode ..... lock inode flags set XFS_INEW unlock inode flags unlock radix tree xfs_setup_inode() inode flags = I_NEW unlock_new_inode() WARNING as inode flags != I_NEW This can lead to inode corruption, inode list corruption, etc, and is generally a bad thing to occur. Fix this by setting XFS_INEW before inserting the inode into the radix tree. This will ensure any concurrent lookup will find the new inode with XFS_INEW set and that forces the lookup to wait until the XFS_INEW flag is removed before allowing the lookup to succeed. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02NFSv4: Return the delegation if the server returns NFS4ERR_OPENMODETrond Myklebust
commit 3114ea7a24d3264c090556a2444fc6d2c06176d4 upstream. If a setattr() fails because of an NFS4ERR_OPENMODE error, it is probably due to us holding a read delegation. Ensure that the recovery routines return that delegation in this case. Reported-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02NFS: Properly handle the case where the delegation is revokedTrond Myklebust
commit a1d0b5eebc4fd6e0edb02688b35f17f67f42aea5 upstream. If we know that the delegation stateid is bad or revoked, we need to remove that delegation as soon as possible, and then mark all the stateids that relied on that delegation for recovery. We cannot use the delegation as part of the recovery process. Also note that NFSv4.1 uses a different error code (NFS4ERR_DELEG_REVOKED) to indicate that the delegation was revoked. Finally, ensure that setlk() and setattr() can both recover safely from a revoked delegation. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02KVM: x86: fix missing checks in syscall emulationStephan Bärwolf
commit c2226fc9e87ba3da060e47333657cd6616652b84 upstream. On hosts without this patch, 32bit guests will crash (and 64bit guests may behave in a wrong way) for example by simply executing following nasm-demo-application: [bits 32] global _start SECTION .text _start: syscall (I tested it with winxp and linux - both always crashed) Disassembly of section .text: 00000000 <_start>: 0: 0f 05 syscall The reason seems a missing "invalid opcode"-trap (int6) for the syscall opcode "0f05", which is not available on Intel CPUs within non-longmodes, as also on some AMD CPUs within legacy-mode. (depending on CPU vendor, MSR_EFER and cpuid) Because previous mentioned OSs may not engage corresponding syscall target-registers (STAR, LSTAR, CSTAR), they remain NULL and (non trapping) syscalls are leading to multiple faults and finally crashs. Depending on the architecture (AMD or Intel) pretended by guests, various checks according to vendor's documentation are implemented to overcome the current issue and behave like the CPUs physical counterparts. [mtosatti: cleanup/beautify code] Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"Stephan Bärwolf
commit bdb42f5afebe208eae90406959383856ae2caf2b upstream. In order to be able to proceed checks on CPU-specific properties within the emulator, function "get_cpuid" is introduced. With "get_cpuid" it is possible to virtually call the guests "cpuid"-opcode without changing the VM's context. [mtosatti: cleanup/beautify code] Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02firewire: ohci: fix too-early completion of IR multichannel buffersClemens Ladisch
commit 0c0efbacab8d70700d13301e0ae7975783c0cb0a upstream. handle_ir_buffer_fill() assumed that a completed descriptor would be indicated by a non-zero transfer_status (as in most other descriptors). However, this field is written by the controller as soon as (the end of) the first packet has been written into the buffer. As a consequence, if we happen to run into such a descriptor when the interrupt handler is executed after such a packet has completed, the descriptor would be taken out of the list of active descriptors as soon as the buffer had been partially filled, so the event for the buffer being completely filled would never be sent. To fix this, handle descriptors only when they have been completely filled, i.e., when res_count == 0. (This also matches the condition that is reported by the controller with an interrupt.) Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02pata_legacy: correctly mask recovery field for HT6560BSergei Shtylyov
commit 9716387311c790de381214c03e7f1b72b91a8189 upstream. According to the HT6560H datasheet, the recovery timing field is 4-bit wide, with a value of 0 meaning 16 cycles. Correct obvious thinko in the recovery field mask. Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02HID: add more hotkeys in Asus AIO keyboardsKeng-Yu Lin
commit 6c30d5a53229aad22bb675e0bd6eb518ecaa4316 upstream. Add support for the camera key. The hotkey for Asus S.H.E(Super Hybrid Engine) mode is mapped to KEY_KEY_PROG1 just for notifying the userspace. Signed-off-by: Keng-Yu Lin <kengyu@canonical.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02HID: add extra hotkeys in Asus AIO keyboardsKeng-Yu Lin
commit 3596bb929f2abd3433c2eaa5755fad48ac207af1 upstream. The Asus All-In-One PC has a wireless keyboard with wifi toggle, brightness up, brightness down and display off hotkeys. This patch adds suppoort for these hotkeys. Signed-off-by: Keng-Yu Lin <kengyu@canonical.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02Bluetooth: Add AR30XX device ID on Asus laptopsKeng-Yu Lin
commit 6b6ba88b5bb8779156b21bb957520a448c3642e2 upstream. The ID is found on Asus K54HR and K53U. Blacklist the AR3011-based device ID [0489:e03d] and add to ath3k.c for firmware loading. Below is the output of usb-devices script: Before the fiwmware loading: T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=12 MxCh= 0 D: Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=0489 ProdID=e03d Rev=00.01 C: #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb I: If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb After the fiwmware loading: T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 5 Spd=12 MxCh= 0 D: Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=0cf3 ProdID=3005 Rev=00.01 C: #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb I: If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb Signed-off-by: Keng-Yu Lin <kengyu@canonical.com> Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02target: Fix 16-bit target ports for SET TARGET PORT GROUPS emulationRoland Dreier
commit 33395fb8a13731c7ef7b175dbf5a4d8a6738fe6c upstream. The old code did (MSB << 8) & 0xff, which always evaluates to 0. Just use get_unaligned_be16() so we don't have to worry about whether our open-coded version is correct or not. Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02target: Don't set WBUS16 or SYNC bits in INQUIRY responseRoland Dreier
commit effc6cc8828257c32c37635e737f14fd6e19ecd7 upstream. SPC-4 says about the WBUS16 and SYNC bits: The meanings of these fields are specific to SPI-5 (see 6.4.3). For SCSI transport protocols other than the SCSI Parallel Interface, these fields are reserved. We don't have a SPI fabric module, so we should never set these bits. (The comment was misleading, since it only mentioned Sync but the actual code set WBUS16 too). Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02drm/radeon/kms: add connector quirk for Fujitsu D3003-S2 boardAlex Deucher
commit 4c1b2d2da3451f5c8dd59bd7e05bd9729d2aee05 upstream. vbios lists DVI-I port as VGA and DVI-D. Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=47007 Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02drm/radeon/kms: fix analog load detection on DVI-I connectorsAlex Deucher
commit e00e8b5e760cbbe9067daeae5454d67c44c8d035 upstream. We digital encoders have a detect function as well (for DP to VGA bridges), so we make sure we choose the analog one here. Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=47007 Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02drm/radeon: Restrict offset for legacy hardware cursor.Michel Dänzer
commit c4353016dac10133fa5d8535af83f0c4845a2915 upstream. The hardware only takes 27 bits for the offset, so larger offsets are truncated, and the hardware cursor shows random bits other than the intended ones. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=46796 Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-04-02md/raid1,raid10: avoid deadlock during resync/recovery.NeilBrown
commit d6b42dcb995e6acd7cc276774e751ffc9f0ef4bf upstream. If RAID1 or RAID10 is used under LVM or some other stacking block device, it is possible to enter a deadlock during resync or recovery. This can happen if the upper level block device creates two requests to the RAID1 or RAID10. The first request gets processed, blocks recovery and queue requests for underlying requests in current->bio_list. A resync request then starts which will wait for those requests and block new IO. But then the second request to the RAID1/10 will be attempted and it cannot progress until the resync request completes, which cannot progress until the underlying device requests complete, which are on a queue behind that second request. So allow that second request to proceed even though there is a resync request about to start. This is suitable for any -stable kernel. Reported-by: Ray Morris <support@bettercgi.com> Tested-by: Ray Morris <support@bettercgi.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02md/bitmap: ensure to load bitmap when creating via sysfs.NeilBrown
commit 4474ca42e2577563a919fd3ed782e2ec55bf11a2 upstream. When commit 69e51b449d383e (md/bitmap: separate out loading a bitmap...) created bitmap_load, it missed calling it after bitmap_create when a bitmap is created through the sysfs interface. So if a bitmap is added this way, we don't allocate memory properly and can crash. This is suitable for any -stable release since 2.6.35. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02tcm_fc: Fix fc_exch memory leak in ft_send_resp_statusNicholas Bellinger
commit 031ed4d565b31880a4136bb7366bc89f5b1dba7d upstream. This patch fixes a bug in tcm_fc where fc_exch memory from fc_exch_mgr->ep_pool is currently being leaked by ft_send_resp_status() usage. Following current code in ft_queue_status() response path, using lport->tt.seq_send() needs to be followed by a lport->tt.exch_done() in order to release fc_exch memory back into libfc_em kmem_cache. ft_send_resp_status() code is currently used in pre submit se_cmd ft_send_work() error exceptions, TM request setup exceptions, and main TM response callback path in ft_queue_tm_resp(). This bugfix addresses the leak in these cases. Cc: Mark D Rustad <mark.d.rustad@intel.com> Cc: Kiran Patil <kiran.patil@intel.com> Cc: Robert Love <robert.w.love@intel.com> Cc: Andy Grover <agrover@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02udlfb: remove sysfs framebuffer device with USB .disconnect()Kay Sievers
commit ce880cb860f36694d2cdebfac9e6ae18176fe4c4 upstream. The USB graphics card driver delays the unregistering of the framebuffer device to a workqueue, which breaks the userspace visible remove uevent sequence. Recent userspace tools started to support USB graphics card hotplug out-of-the-box and rely on proper events sent by the kernel. The framebuffer device is a direct child of the USB interface which is removed immediately after the USB .disconnect() callback. But the fb device in /sys stays around until its final cleanup, at a time where all the parent devices have been removed already. To work around that, we remove the sysfs fb device directly in the USB .disconnect() callback and leave only the cleanup of the internal fb data to the delayed work. Before: add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb) add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb) add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb0 (graphics) remove /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb) remove /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb) remove /2-1.2:1.0/graphics/fb0 (graphics) After: add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb) add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb) add /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb1 (graphics) remove /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/graphics/fb1 (graphics) remove /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0 (usb) remove /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2 (usb) Tested-by: Bernie Thompson <bernie@plugable.com> Acked-by: Bernie Thompson <bernie@plugable.com> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02tcm_loop: Set residual field for SCSI commandsRoland Dreier
commit 6cf3fa6918baab0c447f1206f1cef9166ad04864 upstream. If the target core signals an over- or under-run, tcm_loop should call scsi_set_resid() to tell the SCSI midlayer about the residual data length. The difference can be seen by doing something like strace -eioctl sg_raw -r 1024 /dev/sda 8 0 0 0 1 0 > /dev/null and looking at the "resid=" part of the SG_IO ioctl -- after this patch, the field is correctly reported as 512. Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02ASoC: pxa-ssp: atomically set stream active masksDaniel Mack
commit 273b72c8ce6b28df6b49423d775c3e59072c73c5 upstream. PXA's SSP engine fails to take its current channel phase into account when enabling a stream while the engine is already running. This results in randomly swapped left/right channels on either the record or the playback side, depending on which one was enabled first. The following patch fixes this by factoring out the bit field modifications in question to a separate function that pauses the engine temporarily, modifies the bits and kicks it off again afterwards. Appearantly, a transition of SSCR0_SSE syncs both directions properly. The patch has been rolled out to quite a number of devices over the last weeks and seems to fix the issue reliably. Signed-off-by: Daniel Mack <zonque@gmail.com> Reported-and-tested-by: Sven Neumann <s.neumann@raumfeld.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02hugetlbfs: avoid taking i_mutex from hugetlbfs_read()Aneesh Kumar K.V
commit a05b0855fd15504972dba2358e5faa172a1e50ba upstream. Taking i_mutex in hugetlbfs_read() can result in deadlock with mmap as explained below Thread A: read() on hugetlbfs hugetlbfs_read() called i_mutex grabbed hugetlbfs_read_actor() called __copy_to_user() called page fault is triggered Thread B, sharing address space with A: mmap() the same file ->mmap_sem is grabbed on task_B->mm->mmap_sem hugetlbfs_file_mmap() is called attempt to grab ->i_mutex and block waiting for A to give it up Thread A: pagefault handled blocked on attempt to grab task_A->mm->mmap_sem, which happens to be the same thing as task_B->mm->mmap_sem. Block waiting for B to give it up. AFAIU the i_mutex locking was added to hugetlbfs_read() as per http://lkml.indiana.edu/hypermail/linux/kernel/0707.2/3066.html to take care of the race between truncate and read. This patch fixes this by looking at page->mapping under lock_page() (find_lock_page()) to ensure that the inode didn't get truncated in the range during a parallel read. Ideally we can extend the patch to make sure we don't increase i_size in mmap. But that will break userspace, because applications will now have to use truncate(2) to increase i_size in hugetlbfs. Based on the original patch from Hillf Danton. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02bootmem/sparsemem: remove limit constraint in alloc_bootmem_sectionNishanth Aravamudan
commit f5bf18fa22f8c41a13eb8762c7373eb3a93a7333 upstream. While testing AMS (Active Memory Sharing) / CMO (Cooperative Memory Overcommit) on powerpc, we tripped the following: kernel BUG at mm/bootmem.c:483! cpu 0x0: Vector: 700 (Program Check) at [c000000000c03940] pc: c000000000a62bd8: .alloc_bootmem_core+0x90/0x39c lr: c000000000a64bcc: .sparse_early_usemaps_alloc_node+0x84/0x29c sp: c000000000c03bc0 msr: 8000000000021032 current = 0xc000000000b0cce0 paca = 0xc000000001d80000 pid = 0, comm = swapper kernel BUG at mm/bootmem.c:483! enter ? for help [c000000000c03c80] c000000000a64bcc .sparse_early_usemaps_alloc_node+0x84/0x29c [c000000000c03d50] c000000000a64f10 .sparse_init+0x12c/0x28c [c000000000c03e20] c000000000a474f4 .setup_arch+0x20c/0x294 [c000000000c03ee0] c000000000a4079c .start_kernel+0xb4/0x460 [c000000000c03f90] c000000000009670 .start_here_common+0x1c/0x2c This is BUG_ON(limit && goal + size > limit); and after some debugging, it seems that goal = 0x7ffff000000 limit = 0x80000000000 and sparse_early_usemaps_alloc_node -> sparse_early_usemaps_alloc_pgdat_section calls return alloc_bootmem_section(usemap_size() * count, section_nr); This is on a system with 8TB available via the AMS pool, and as a quirk of AMS in firmware, all of that memory shows up in node 0. So, we end up with an allocation that will fail the goal/limit constraints. In theory, we could "fall-back" to alloc_bootmem_node() in sparse_early_usemaps_alloc_node(), but since we actually have HOTREMOVE defined, we'll BUG_ON() instead. A simple solution appears to be to unconditionally remove the limit condition in alloc_bootmem_section, meaning allocations are allowed to cross section boundaries (necessary for systems of this size). Johannes Weiner pointed out that if alloc_bootmem_section() no longer guarantees section-locality, we need check_usemap_section_nr() to print possible cross-dependencies between node descriptors and the usemaps allocated through it. That makes the two loops in sparse_early_usemaps_alloc_node() identical, so re-factor the code a bit. [akpm@linux-foundation.org: code simplification] Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Anton Blanchard <anton@au1.ibm.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ben Herrenschmidt <benh@kernel.crashing.org> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-04-02mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read modeAndrea Arcangeli
commit 1a5a9906d4e8d1976b701f889d8f35d54b928f25 upstream. In some cases it may happen that pmd_none_or_clear_bad() is called with the mmap_sem hold in read mode. In those cases the huge page faults can allocate hugepmds under pmd_none_or_clear_bad() and that can trigger a false positive from pmd_bad() that will not like to see a pmd materializing as trans huge. It's not khugepaged causing the problem, khugepaged holds the mmap_sem in write mode (and all those sites must hold the mmap_sem in read mode to prevent pagetables to go away from under them, during code review it seems vm86 mode on 32bit kernels requires that too unless it's restricted to 1 thread per process or UP builds). The race is only with the huge pagefaults that can convert a pmd_none() into a pmd_trans_huge(). Effectively all these pmd_none_or_clear_bad() sites running with mmap_sem in read mode are somewhat speculative with the page faults, and the result is always undefined when they run simultaneously. This is probably why it wasn't common to run into this. For example if the madvise(MADV_DONTNEED) runs zap_page_range() shortly before the page fault, the hugepage will not be zapped, if the page fault runs first it will be zapped. Altering pmd_bad() not to error out if it finds hugepmds won't be enough to fix this, because zap_pmd_range would then proceed to call zap_pte_range (which would be incorrect if the pmd become a pmd_trans_huge()). The simplest way to fix this is to read the pmd in the local stack (regardless of what we read, no need of actual CPU barriers, only compiler barrier needed), and be sure it is not changing under the code that computes its value. Even if the real pmd is changing under the value we hold on the stack, we don't care. If we actually end up in zap_pte_range it means the pmd was not none already and it was not huge, and it can't become huge from under us (khugepaged locking explained above). All we need is to enforce that there is no way anymore that in a code path like below, pmd_trans_huge can be false, but pmd_none_or_clear_bad can run into a hugepmd. The overhead of a barrier() is just a compiler tweak and should not be measurable (I only added it for THP builds). I don't exclude different compiler versions may have prevented the race too by caching the value of *pmd on the stack (that hasn't been verified, but it wouldn't be impossible considering pmd_none_or_clear_bad, pmd_bad, pmd_trans_huge, pmd_none are all inlines and there's no external function called in between pmd_trans_huge and pmd_none_or_clear_bad). if (pmd_trans_huge(*pmd)) { if (next-addr != HPAGE_PMD_SIZE) { VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem)); split_huge_page_pmd(vma->vm_mm, pmd); } else if (zap_huge_pmd(tlb, vma, pmd, addr)) continue; /* fall through */ } if (pmd_none_or_clear_bad(pmd)) Because this race condition could be exercised without special privileges this was reported in CVE-2012-1179. The race was identified and fully explained by Ulrich who debugged it. I'm quoting his accurate explanation below, for reference. ====== start quote ======= mapcount 0 page_mapcount 1 kernel BUG at mm/huge_memory.c:1384! At some point prior to the panic, a "bad pmd ..." message similar to the following is logged on the console: mm/memory.c:145: bad pmd ffff8800376e1f98(80000000314000e7). The "bad pmd ..." message is logged by pmd_clear_bad() before it clears the page's PMD table entry. 143 void pmd_clear_bad(pmd_t *pmd) 144 { -> 145 pmd_ERROR(*pmd); 146 pmd_clear(pmd); 147 } After the PMD table entry has been cleared, there is an inconsistency between the actual number of PMD table entries that are mapping the page and the page's map count (_mapcount field in struct page). When the page is subsequently reclaimed, __split_huge_page() detects this inconsistency. 1381 if (mapcount != page_mapcount(page)) 1382 printk(KERN_ERR "mapcount %d page_mapcount %d\n", 1383 mapcount, page_mapcount(page)); -> 1384 BUG_ON(mapcount != page_mapcount(page)); The root cause of the problem is a race of two threads in a multithreaded process. Thread B incurs a page fault on a virtual address that has never been accessed (PMD entry is zero) while Thread A is executing an madvise() system call on a virtual address within the same 2 MB (huge page) range. virtual address space .---------------------. | | | | .-|---------------------| | | | | | |<-- B(fault) | | | 2 MB | |/////////////////////|-. huge < |/////////////////////| > A(range) page | |/////////////////////|-' | | | | | | '-|---------------------| | | | | '---------------------' - Thread A is executing an madvise(..., MADV_DONTNEED) system call on the virtual address range "A(range)" shown in the picture. sys_madvise // Acquire the semaphore in shared mode. down_read(&current->mm->mmap_sem) ... madvise_vma switch (behavior) case MADV_DONTNEED: madvise_dontneed zap_page_range unmap_vmas unmap_page_range zap_pud_range zap_pmd_range // // Assume that this huge page has never been accessed. // I.e. content of the PMD entry is zero (not mapped). // if (pmd_trans_huge(*pmd)) { // We don't get here due to the above assumption. } // // Assume that Thread B incurred a page fault and .---------> // sneaks in here as shown below. | // | if (pmd_none_or_clear_bad(pmd)) | { | if (unlikely(pmd_bad(*pmd))) | pmd_clear_bad | { | pmd_ERROR | // Log "bad pmd ..." message here. | pmd_clear | // Clear the page's PMD entry. | // Thread B incremented the map count | // in page_add_new_anon_rmap(), but | // now the page is no longer mapped | // by a PMD entry (-> inconsistency). | } | } | v - Thread B is handling a page fault on virtual address "B(fault)" shown in the picture. ... do_page_fault __do_page_fault // Acquire the semaphore in shared mode. down_read_trylock(&mm->mmap_sem) ... handle_mm_fault if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) // We get here due to the above assumption (PMD entry is zero). do_huge_pmd_anonymous_page alloc_hugepage_vma // Allocate a new transparent huge page here. ... __do_huge_pmd_anonymous_page ... spin_lock(&mm->page_table_lock) ... page_add_new_anon_rmap // Here we increment the page's map count (starts at -1). atomic_set(&page->_mapcount, 0) set_pmd_at // Here we set the page's PMD entry which will be cleared // when Thread A calls pmd_clear_bad(). ... spin_unlock(&mm->page_table_lock) The mmap_sem does not prevent the race because both threads are acquiring it in shared mode (down_read). Thread B holds the page_table_lock while the page's map count and PMD table entry are updated. However, Thread A does not synchronize on that lock. ====== end quote ======= [akpm@linux-foundation.org: checkpatch fixes] Reported-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Jones <davej@redhat.com> Acked-by: Larry Woodman <lwoodman@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mark Salter <msalter@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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