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2009-07-29kmemleak: Protect the seq start/next/stop sequence by rcu_read_lock()Catalin Marinas
Objects passed to kmemleak_seq_next() have an incremented reference count (hence not freed) but they may point via object_list.next to other freed objects. To avoid this, the whole start/next/stop sequence must be protected by rcu_read_lock(). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-08kmemleak: Allow partial freeing of memory blocksCatalin Marinas
Functions like free_bootmem() are allowed to free only part of a memory block. This patch adds support for this via the kmemleak_free_part() callback which removes the original object and creates one or two additional objects as a result of the memory block split. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ingo Molnar <mingo@elte.hu> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-07-08kmemleak: Scan objects allocated during a scanning episodeCatalin Marinas
Many of the false positives in kmemleak happen on busy systems where objects are allocated during a kmemleak scanning episode. These objects aren't scanned by default until the next memory scan. When such object is added, for example, at the head of a list, it is possible that all the other objects in the list become unreferenced until the next scan. This patch adds checking for newly allocated objects at the end of the scan and repeats the scanning on these objects. If Linux allocates new objects at a higher rate than their scanning, it stops after a predefined number of passes. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-08kmemleak: Do not acquire scan_mutex in kmemleak_open()Catalin Marinas
Initially, the scan_mutex was acquired in kmemleak_open() and released in kmemleak_release() (corresponding to /sys/kernel/debug/kmemleak operations). This was causing some lockdep reports when the file was closed from a different task than the one opening it. This patch moves the scan_mutex acquiring in kmemleak_write() or kmemleak_seq_start() with releasing in kmemleak_seq_stop(). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-08kmemleak: Remove the reported leaks number limitationCatalin Marinas
Since the leaks are no longer printed to the syslog, there is no point in keeping this limitation. All the suspected leaks are shown on /sys/kernel/debug/kmemleak file. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-07kmemleak: Add more cond_resched() calls in the scanning threadCatalin Marinas
Following recent fix to no longer reschedule in the scan_block() function, the system may become unresponsive with !PREEMPT. This patch re-adds the cond_resched() call to scan_block() but conditioned by the allow_resched parameter. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-07kmemleak: Renice the scanning thread to +10Catalin Marinas
This is a long-running thread but not high-priority. So it makes sense to renice it to +10. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-01kmemleak: Fix scheduling-while-atomic bugIngo Molnar
One of the kmemleak changes caused the following scheduling-while-holding-the-tasklist-lock regression on x86: BUG: sleeping function called from invalid context at mm/kmemleak.c:795 in_atomic(): 1, irqs_disabled(): 0, pid: 1737, name: kmemleak 2 locks held by kmemleak/1737: #0: (scan_mutex){......}, at: [<c10c4376>] kmemleak_scan_thread+0x45/0x86 #1: (tasklist_lock){......}, at: [<c10c3bb4>] kmemleak_scan+0x1a9/0x39c Pid: 1737, comm: kmemleak Not tainted 2.6.31-rc1-tip #59266 Call Trace: [<c105ac0f>] ? __debug_show_held_locks+0x1e/0x20 [<c102e490>] __might_sleep+0x10a/0x111 [<c10c38d5>] scan_yield+0x17/0x3b [<c10c3970>] scan_block+0x39/0xd4 [<c10c3bc6>] kmemleak_scan+0x1bb/0x39c [<c10c4331>] ? kmemleak_scan_thread+0x0/0x86 [<c10c437b>] kmemleak_scan_thread+0x4a/0x86 [<c104d73e>] kthread+0x6e/0x73 [<c104d6d0>] ? kthread+0x0/0x73 [<c100959f>] kernel_thread_helper+0x7/0x10 kmemleak: 834 new suspected memory leaks (see /sys/kernel/debug/kmemleak) The bit causing it is highly dubious: static void scan_yield(void) { might_sleep(); if (time_is_before_eq_jiffies(next_scan_yield)) { schedule(); next_scan_yield = jiffies + jiffies_scan_yield; } } It called deep inside the codepath and in a conditional way, and that is what crapped up when one of the new scan_block() uses grew a tasklist_lock dependency. This minimal patch removes that yielding stuff and adds the proper cond_resched(). The background scanning thread could probably also be reniced to +10. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-29kmemleak: Do not warn if an unknown object is freedCatalin Marinas
vmap'ed memory blocks are not tracked by kmemleak (yet) but they may be released with vfree() which is tracked. The corresponding kmemleak warning is only enabled in debug mode. Future patch will add support for ioremap and vmap. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-29kmemleak: Do not report new leaked objects if the scanning was stoppedCatalin Marinas
If the scanning was stopped with a signal, it is possible that some objects are left with a white colour (potential leaks) and reported. Add a check to avoid reporting such objects. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-26kmemleak: Slightly change the policy on newly allocated objectsCatalin Marinas
Newly allocated objects are more likely to be reported as false positives. Kmemleak ignores the reporting of objects younger than 5 seconds. However, this age was calculated after the memory scanning completed which usually takes longer than 5 seconds. This patch make the minimum object age calculation in relation to the start of the memory scanning. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-26kmemleak: Do not trigger a scan when reading the debug/kmemleak fileCatalin Marinas
Since there is a kernel thread for automatically scanning the memory, it makes sense for the debug/kmemleak file to only show its findings. This patch also adds support for "echo scan > debug/kmemleak" to trigger an intermediate memory scan and eliminates the kmemleak_mutex (scan_mutex covers all the cases now). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-26kmemleak: Simplify the reports logged by the scanning threadCatalin Marinas
Because of false positives, the memory scanning thread may print too much information. This patch changes the scanning thread to only print the number of newly suspected leaks. Further information can be read from the /sys/kernel/debug/kmemleak file. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-26kmemleak: Enable task stacks scanning by defaultCatalin Marinas
This is to reduce the number of false positives reported. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-25kmemleak: Allow the early log buffer to be configurable.Catalin Marinas
(feature suggested by Sergey Senozhatsky) Kmemleak needs to track all the memory allocations but some of these happen before kmemleak is initialised. These are stored in an internal buffer which may be exceeded in some kernel configurations. This patch adds a configuration option with a default value of 400 and also removes the stack dump when the early log buffer is exceeded. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@mail.by>
2009-06-23kmemleak: use pr_fmtJoe Perches
Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-17kmemleak: Fix some typos in commentsCatalin Marinas
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-06-17kmemleak: Rename kmemleak_panic to kmemleak_stopCatalin Marinas
This is to avoid the confusion created by the "panic" word. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-06-17kmemleak: Only use GFP_KERNEL|GFP_ATOMIC for the internal allocationsCatalin Marinas
Kmemleak allocates memory for pointer tracking and it tries to avoid using GFP_ATOMIC if the caller doesn't require it. However other gfp flags may be passed by the caller which aren't required by kmemleak. This patch filters the gfp flags so that only GFP_KERNEL | GFP_ATOMIC are used. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-06-11kmemleak: Add the base supportCatalin Marinas
This patch adds the base support for the kernel memory leak detector. It traces the memory allocation/freeing in a way similar to the Boehm's conservative garbage collector, the difference being that the unreferenced objects are not freed but only shown in /sys/kernel/debug/kmemleak. Enabling this feature introduces an overhead to memory allocations. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ingo Molnar <mingo@elte.hu> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>