- 30 Apr, 2008 40 commits
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Thomas Gleixner authored
We can see an ever repeating problem pattern with objects of any kind in the kernel: 1) freeing of active objects 2) reinitialization of active objects Both problems can be hard to debug because the crash happens at a point where we have no chance to decode the root cause anymore. One problem spot are kernel timers, where the detection of the problem often happens in interrupt context and usually causes the machine to panic. While working on a timer related bug report I had to hack specialized code into the timer subsystem to get a reasonable hint for the root cause. This debug hack was fine for temporary use, but far from a mergeable solution due to the intrusiveness into the timer code. The code further lacked the ability to detect and report the root cause instantly and keep the system operational. Keeping the system operational is important to get hold of the debug information without special debugging aids like serial consoles and special knowledge of the bug reporter. The problems described above are not restricted to timers, but timers tend to expose it usually in a full system crash. Other objects are less explosive, but the symptoms caused by such mistakes can be even harder to debug. Instead of creating specialized debugging code for the timer subsystem a generic infrastructure is created which allows developers to verify their code and provides an easy to enable debug facility for users in case of trouble. The debugobjects core code keeps track of operations on static and dynamic objects by inserting them into a hashed list and sanity checking them on object operations and provides additional checks whenever kernel memory is freed. The tracked object operations are: - initializing an object - adding an object to a subsystem list - deleting an object from a subsystem list Each operation is sanity checked before the operation is executed and the subsystem specific code can provide a fixup function which allows to prevent the damage of the operation. When the sanity check triggers a warning message and a stack trace is printed. The list of operations can be extended if the need arises. For now it's limited to the requirements of the first user (timers). The core code enqueues the objects into hash buckets. The hash index is generated from the address of the object to simplify the lookup for the check on kfree/vfree. Each bucket has it's own spinlock to avoid contention on a global lock. The debug code can be compiled in without being active. The runtime overhead is minimal and could be optimized by asm alternatives. A kernel command line option enables the debugging code. Thanks to Ingo Molnar for review, suggestions and cleanup patches. Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Thomas Gleixner authored
This is a preperatory patch for the debugobjects infrastructure. The flag prevents debug_free checks on kmem_caches. This is necessary to avoid resursive calls into a debug mechanism which uses a kmem_cache itself. Signed-off-by:
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Harvey Harrison authored
__FUNCTION__ is gcc-specific, use __func__ Signed-off-by:
Harvey Harrison <harvey.harrison@gmail.com> Cc: Ben Dooks <ben-linux@fluff.org> Signed-off-by:
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Harvey Harrison authored
Also, change the variable names used in the min/max macros to avoid shadowed variable warnings when min/max min_t/max_t are nested. Small formatting changes to make all the macros have a similar form. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix v4l build] Signed-off-by:
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Andrew Morton authored
Use kmem_cache_zalloc(), remove large amounts of initialisation code and ifdeffery. Note: this assumes that memset(*atomic_t, 0) correctly initialises the atomic_t. This is true for all present archtiectures and if it becomes false for a future architecture then we'll need to make large changes all over the place anyway. Acked-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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Andrew Morton authored
fs/hfsplus/btree.c: In function 'hfsplus_bmap_alloc': fs/hfsplus/btree.c:239: warning: comparison is always false due to limited range of data type But this might hide a real bug? Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by:
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Andrew Morton authored
fs/hfs/btree.c: In function 'hfs_bmap_alloc': fs/hfs/btree.c:263: warning: comparison is always false due to limited range of data type The patch makes the warning go away, but the code might actually be buggy? Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by:
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Markus Armbruster authored
Fix update_console_cmdline() not to to read beyond the terminating zero of its name argument. Signed-off-by:
Markus Armbruster <armbru@redhat.com> Signed-off-by:
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Samuel Thibault authored
This adds a minimalistic braille screen reader support. This is meant to be used by blind people e.g. on boot failures or when / cannot be mounted etc and thus the userland screen readers can not work. [akpm@linux-foundation.org: fix exports] Signed-off-by:
Samuel Thibault <samuel.thibault@ens-lyon.org> Cc: Jiri Kosina <jikos@jikos.cz> Cc: Dmitry Torokhov <dtor@mail.ru> Acked-by:
Alan Cox <alan@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by:
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Jeff Dike authored
Lots of asm-*/futex.h call pagefault_enable and pagefault_disable, which are declared in linux/uaccess.h, without including linux/uaccess.h. They all include asm/uaccess.h, so this patch replaces asm/uaccess.h with linux/uaccess.h. Signed-off-by:
Jeff Dike <jdike@linux.intel.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
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Marcin Slusarz authored
replace all: big/little_endian_variable = cpu_to_[bl]eX([bl]eX_to_cpu(big/little_endian_variable) + expression_in_cpu_byteorder); with: [bl]eX_add_cpu(&big/little_endian_variable, expression_in_cpu_byteorder); generated with semantic patch Signed-off-by:
Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by:
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Marcin Slusarz authored
replace all: little_endian_variable = cpu_to_leX(leX_to_cpu(little_endian_variable) + expression_in_cpu_byteorder); with: leX_add_cpu(&little_endian_variable, expression_in_cpu_byteorder); generated with semantic patch Signed-off-by:
Jan Kara <jack@suse.cz> Signed-off-by:
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Marcin Slusarz authored
replace all: big_endian_variable = cpu_to_beX(beX_to_cpu(big_endian_variable) + expression_in_cpu_byteorder); with: beX_add_cpu(&big_endian_variable, expression_in_cpu_byteorder); generated with semantic patch Signed-off-by:
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Marcin Slusarz authored
replace all: big_endian_variable = cpu_to_beX(beX_to_cpu(big_endian_variable) + expression_in_cpu_byteorder); with: beX_add_cpu(&big_endian_variable, expression_in_cpu_byteorder); generated with semantic patch Signed-off-by:
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Christoph Hellwig authored
Use the proper helper to open a blockdevice by name for filesystem use, this makes sure it's properly claimed (also added for open-by-number) and gets rid of the struct file abuse. Tested by mounting a reiserfs filesystem with external journal. Signed-off-by:
Christoph Hellwig <hch@lst.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Jeff Mahoney <jeffm@suse.com> Acked-by:
Edward Shishkin <edward.shishkin@gmail.com> Signed-off-by:
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Miklos Szeredi authored
fs/fuse/dev.c:306:2: warning: context imbalance in 'wait_answer_interruptible' - unexpected unlock fs/fuse/dev.c:361:2: warning: context imbalance in 'request_wait_answer' - unexpected unlock fs/fuse/dev.c:1002:4: warning: context imbalance in 'end_io_requests' - unexpected unlock Signed-off-by:
Miklos Szeredi <mszeredi@suse.cz> Signed-off-by:
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Miklos Szeredi authored
Fuse doesn't use i_mutex to protect setting i_size, and so generic_file_llseek() can be racy: it doesn't use i_size_read(). So do a fuse specific llseek method, which does use i_size_read(). [akpm@linux-foundation.org: make `retval' loff_t] Signed-off-by:
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Miklos Szeredi authored
Node ID is 64bit but it is passed as unsigned long to some functions. This breakage wasn't noticed, because libfuse uses unsigned long too. Signed-off-by:
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Miklos Szeredi authored
Fix a bug that Werner Baumann reported: fuse can send a bigger write request than the maximum specified. This only affected direct_io operation. In addition set a sane minimum for the max_read and max_write tunables, so I/O always makes some progress. Signed-off-by:
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Miklos Szeredi authored
If the READ request returned a short count, then either - cached size is incorrect - filesystem is buggy, as short reads are only allowed on EOF So assume that the size is wrong and refresh it, so that cached read() doesn't zero fill the missing chunk. Signed-off-by:
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Nick Piggin authored
Introduce fuse_perform_write. With fusexmp (a passthrough filesystem), large (1MB) writes into a backing tmpfs filesystem are sped up by almost 4 times (256MB/s vs 71MB/s). [mszeredi@suse.cz]: - split into smaller functions - testing - duplicate generic_file_aio_write(), so that there's no need to add a new ->perform_write() a_op. Comment from hch. Signed-off-by:
Nick Piggin <npiggin@suse.de> Signed-off-by:
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Miklos Szeredi authored
Extract common code for setting i_size in write functions into a common helper. Signed-off-by:
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Miklos Szeredi authored
Quoting Linus (3 years ago, FUSE inclusion discussions): "User-space filesystems are hard to get right. I'd claim that they are almost impossible, unless you limit them somehow (shared writable mappings are the nastiest part - if you don't have those, you can reasonably limit your problems by limiting the number of dirty pages you accept through normal "write()" calls)." Instead of attempting the impossible, I've just waited for the dirty page accounting infrastructure to materialize (thanks to Peter Zijlstra and others). This nicely solved the biggest problem: limiting the number of pages used for write caching. Some small details remained, however, which this largish patch attempts to address. It provides a page writeback implementation for fuse, which is completely safe against VM related deadlocks. Performance may not be very good for certain usage patterns, but generally it should be acceptable. It has been tested extensively with fsx-linux and bash-shared-mapping. Fuse page writeback design -------------------------- fuse_writepage() allocates a new temporary page with GFP_NOFS|__GFP_HIGHMEM. It copies the contents of the original page, and queues a WRITE request to the userspace filesystem using this temp page. The writeback is finished instantly from the MM's point of view: the page is removed from the radix trees, and the PageDirty and PageWriteback flags are cleared. For the duration of the actual write, the NR_WRITEBACK_TEMP counter is incremented. The per-bdi writeback count is not decremented until the actual write completes. On dirtying the page, fuse waits for a previous write to finish before proceeding. This makes sure, there can only be one temporary page used at a time for one cached page. This approach is wasteful in both memory and CPU bandwidth, so why is this complication needed? The basic problem is that there can be no guarantee about the time in which the userspace filesystem will complete a write. It may be buggy or even malicious, and fail to complete WRITE requests. We don't want unrelated parts of the system to grind to a halt in such cases. Also a filesystem may need additional resources (particularly memory) to complete a WRITE request. There's a great danger of a deadlock if that allocation may wait for the writepage to finish. Currently there are several cases where the kernel can block on page writeback: - allocation order is larger than PAGE_ALLOC_COSTLY_ORDER - page migration - throttle_vm_writeout (through NR_WRITEBACK) - sync(2) Of course in some cases (fsync, msync) we explicitly want to allow blocking. So for these cases new code has to be added to fuse, since the VM is not tracking writeback pages for us any more. As an extra safetly measure, the maximum dirty ratio allocated to a single fuse filesystem is set to 1% by default. This way one (or several) buggy or malicious fuse filesystems cannot slow down the rest of the system by hogging dirty memory. With appropriate privileges, this limit can be raised through '/sys/class/bdi/<bdi>/max_ratio'. Signed-off-by:
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Miklos Szeredi authored
A few fields in /proc/meminfo were not documented. Fix. Signed-off-by:
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Miklos Szeredi authored
Fuse will use temporary buffers to write back dirty data from memory mappings (normal writes are done synchronously). This is needed, because there cannot be any guarantee about the time in which a write will complete. By using temporary buffers, from the MM's point if view the page is written back immediately. If the writeout was due to memory pressure, this effectively migrates data from a full zone to a less full zone. This patch adds a new counter (NR_WRITEBACK_TEMP) for the number of pages used as temporary buffers. [Lee.Schermerhorn@hp.com: add vmstat_text for NR_WRITEBACK_TEMP] Signed-off-by:
Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by:
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Miklos Szeredi authored
Fuse needs this for writable mmap support. Signed-off-by:
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Miklos Szeredi authored
Add a new BDI capability flag: BDI_CAP_NO_ACCT_WB. If this flag is set, then don't update the per-bdi writeback stats from test_set_page_writeback() and test_clear_page_writeback(). Misc cleanups: - convert bdi_cap_writeback_dirty() and friends to static inline functions - create a flag that includes all three dirty/writeback related flags, since almst all users will want to have them toghether Signed-off-by:
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Miklos Szeredi authored
Move BDI statistics to debugfs: /sys/kernel/debug/bdi/<bdi>/stats Use postcore_initcall() to initialize the sysfs class and debugfs, because debugfs is initialized in core_initcall(). Update descriptions in ABI documentation. Signed-off-by:
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Peter Zijlstra authored
Add "max_ratio" to /sys/class/bdi. This indicates the maximum percentage of the global dirty threshold allocated to this bdi. [mszeredi@suse.cz] - fix parsing in max_ratio_store(). - export bdi_set_max_ratio() to modules - limit bdi_dirty with bdi->max_ratio - document new sysfs attribute Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
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Peter Zijlstra authored
Under normal circumstances each device is given a part of the total write-back cache that relates to its current avg writeout speed in relation to the other devices. min_ratio - allows one to assign a minimum portion of the write-back cache to a particular device. This is useful in situations where you might want to provide a minimum QoS. (One request for this feature came from flash based storage people who wanted to avoid writing out at all costs - they of course needed some pdflush hacks as well) max_ratio - allows one to assign a maximum portion of the dirty limit to a particular device. This is useful in situations where you want to avoid one device taking all or most of the write-back cache. Eg. an NFS mount that is prone to get stuck, or a FUSE mount which you don't trust to play fair. Add "min_ratio" to /sys/class/bdi. This indicates the minimum percentage of the global dirty threshold allocated to this bdi. [mszeredi@suse.cz] - fix parsing in min_ratio_store() - document new sysfs attribute Signed-off-by:
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Miklos Szeredi authored
Register FUSE's backing_dev_info under sysfs with the name "fuse-MAJOR:MINOR" Make the fuse control filesystem use s_dev instead of a fuse specific ID. This makes it easier to match directories under /sys/fs/fuse/connections/ with directories under /sys/class/bdi, and with actual mounts. Signed-off-by:
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Miklos Szeredi authored
Register NFS' backing_dev_info under sysfs with the name "nfs-MAJOR:MINOR" Signed-off-by:
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Peter Zijlstra authored
Provide a place in sysfs (/sys/class/bdi) for the backing_dev_info object. This allows us to see and set the various BDI specific variables. In particular this properly exposes the read-ahead window for all relevant users and /sys/block/<block>/queue/read_ahead_kb should be deprecated. With patient help from Kay Sievers and Greg KH [mszeredi@suse.cz] - split off NFS and FUSE changes into separate patches - document new sysfs attributes under Documentation/ABI - do bdi_class_init as a core_initcall, otherwise the "default" BDI won't be initialized - remove bdi_init_fmt macro, it's not used very much [akpm@linux-foundation.org: fix ia64 warning] Signed-off-by:
Greg KH <greg@kroah.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by:
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Pavel Emelyanov authored
These values represent the nesting level of a namespace and pids living in it, and it's always non-negative. Turning this from int to unsigned int saves some space in pid.c (11 bytes on x86 and 64 on ia64) by letting the compiler optimize the pid_nr_ns a bit. E.g. on ia64 this removes the sign extension calls, which compiler adds to optimize access to pid->nubers[ns->level]. Signed-off-by:
Pavel Emelyanov <xemul@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
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Adrian Bunk authored
With the needlessly global marker_debug being static gcc can optimize the unused code away. Signed-off-by:
Adrian Bunk <bunk@kernel.org> Acked-by:
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Christoph Hellwig authored
Signed-off-by:
Jiri Slaby <jirislaby@gmail.com> Signed-off-by:
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Oleg Nesterov authored
1. sys_getpgid() needs rcu_read_lock() to derive the pgrp _nr, even if the task is current, otherwise we can race with another thread which does sys_setpgid(). 2. Use rcu_read_lock() instead of tasklist_lock when pid != 0, make sure that we don't use the NULL pid if the task exits right after successful find_task_by_vpid(). Signed-off-by:
Oleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by:
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Oleg Nesterov authored
1. sys_getsid() needs rcu_read_lock() to derive the session _nr, even if the task is current, otherwise we can race with another thread which does sys_setsid(). 2. The task can exit between find_task_by_vpid() and task_session_vnr(), in that unlikely case sys_getsid() returns 0 instead of -ESRCH. Signed-off-by:
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Oleg Nesterov authored
Use change_pid() instead of detach_pid() + attach_pid() in __set_special_pids(). This way task_session() is not NULL in between. Signed-off-by:
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Oleg Nesterov authored
Use change_pid() instead of detach_pid() + attach_pid() in sys_setpgid(). This way task_pgrp() is not NULL in between. Signed-off-by:
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