- 07 Nov, 2015 40 commits
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Davidlohr Bueso authored
d0edd852 ("ipc: convert invalid scenarios to use WARN_ON") relaxed the nil dst parameter check, originally being a full BUG_ON. However, this check seems quite unnecessary when the only purpose is for ceckpoint/restore (MSG_COPY flag): o The copy variable is set initially to nil, apparently as a way of ensuring that prepare_copy is previously called. Which is in fact done, unconditionally at the beginning of do_msgrcv. o There is no concurrency with 'copy' (stack allocated in do_msgrcv). Furthermore, any errors in 'copy' (and thus prepare_copy/copy_msg) should always handled by IS_ERR() family. Therefore remove this check altogether as it can never occur with the current users. Signed-off-by:
Davidlohr Bueso <dbueso@suse.de> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Anish Bhatt authored
alder32 was renamed to zlib_adler32 since before 2.6.11. Signed-off-by:
Anish Bhatt <anish@chelsio.com> Signed-off-by:
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Vitaly Kuznetsov authored
In some cases we may end up killing the CPU holding the console lock while still having valuable data in logbuf. E.g. I'm observing the following: - A crash is happening on one CPU and console_unlock() is being called on some other. - console_unlock() tries to print out the buffer before releasing the lock and on slow console it takes time. - in the meanwhile crashing CPU does lots of printk()-s with valuable data (which go to the logbuf) and sends IPIs to all other CPUs. - console_unlock() finishes printing previous chunk and enables interrupts before trying to print out the rest, the CPU catches the IPI and never releases console lock. This is not the only possible case: in VT/fb subsystems we have many other console_lock()/console_unlock() users. Non-masked interrupts (or receiving NMI in case of extreme slowness) will have the same result. Getting the whole console buffer printed out on crash should be top priority. [akpm@linux-foundation.org: tweak comment text] Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Baoquan He <bhe@redhat.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by:
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Robin Murphy authored
Like dma_unmap_sg, dma_sync_sg* should be called with the original number of entries passed to dma_map_sg, so do the same check in the sync path as we do in the unmap path. Signed-off-by:
Robin Murphy <robin.murphy@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Sakari Ailus <sakari.ailus@iki.fi> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by:
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Robin Murphy authored
Many DMA controllers and other devices set max_segment_size to indicate their scatter-gather capability, but have no interest in segment_boundary_mask. However, the existence of a dma_parms structure precludes the use of any default value, leaving them as zeros (assuming a properly kzalloc'ed structure). If a well-behaved IOMMU (or SWIOTLB) then tries to respect this by ensuring a mapped segment does not cross a zero-byte boundary, hilarity ensues. Since zero is a nonsensical value for either parameter, treat it as an indicator for "default", as might be expected. In the process, clean up a bit by replacing the bare constants with slightly more meaningful macros and removing the superfluous "else" statements. [akpm@linux-foundation.org: dma-mapping.h needs sizes.h for SZ_64K] Signed-off-by:
Sumit Semwal <sumit.semwal@linaro.org> Acked-by:
Marek Szyprowski <m.szyprowski@samsung.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Sakari Ailus <sakari.ailus@iki.fi> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by:
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Ben Segall authored
setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of the current pid namespace. This is in contrast to both the other modes of setpriority and the example of kill(-1). Fix this. getpriority and ioprio have the same failure mode, fix them too. Eric said: : After some more thinking about it this patch sounds justifiable. : : My goal with namespaces is not to build perfect isolation mechanisms : as that can get into ill defined territory, but to build well defined : mechanisms. And to handle the corner cases so you can use only : a single namespace with well defined results. : : In this case you have found the two interfaces I am aware of that : identify processes by uid instead of by pid. Which quite frankly is : weird. Unfortunately the weird unexpected cases are hard to handle : in the usual way. : : I was hoping for a little more information. Changes like this one we : have to be careful of because someone might be depending on the current : behavior. I don't think they are and I do think this make sense as part : of the pid namespace. Signed-off-by:
Ben Segall <bsegall@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ambrose Feinstein <ambrose@google.com> Acked-by:
"Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
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Minfei Huang authored
kexec output message misses the prefix "kexec", when Dave Young split the kexec code. Now, we use file name as the output message prefix. Currently, the format of output message: [ 140.290795] SYSC_kexec_load: hello, world [ 140.291534] kexec: sanity_check_segment_list: hello, world Ideally, the format of output message: [ 30.791503] kexec: SYSC_kexec_load, Hello, world [ 79.182752] kexec_core: sanity_check_segment_list, Hello, world Remove the custom prefix "kexec" in output message. Signed-off-by:
Minfei Huang <mnfhuang@gmail.com> Acked-by:
Dave Young <dyoung@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
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Greg Thelen authored
Since 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill processes") seq_buf_alloc() avoids calling the oom killer for PAGE_SIZE or smaller allocations; but larger allocations can use the oom killer via vmalloc(). Thus reads of small files can return ENOMEM, but larger files use the oom killer to avoid ENOMEM. The effect of this bug is that reads from /proc and other virtual filesystems can return ENOMEM instead of the preferred behavior - oom killing something (possibly the calling process). I don't know of anyone except Google who has noticed the issue. I suspect the fix is more needed in smaller systems where there isn't any reclaimable memory. But these seem like the kinds of systems which probably don't use the oom killer for production situations. Memory overcommit requires use of the oom killer to select a victim regardless of file size. Enable oom killer for small seq_buf_alloc() allocations. Fixes: 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill processes") Signed-off-by:
David Rientjes <rientjes@google.com> Signed-off-by:
Greg Thelen <gthelen@google.com> Acked-by:
Eric Dumazet <edumazet@google.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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Andy Shevchenko authored
strint_escape_str() escapes input string by given criteria. In case of seq_escape() the criteria is to convert some characters to their octal representation. Signed-off-by:
Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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Andy Shevchenko authored
This improves code readability. Signed-off-by:
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Oleg Nesterov authored
Change zap_threads() paths to use for_each_thread() rather than while_each_thread(). While at it, change zap_threads() to avoid the nested if's to make the code more readable and lessen the indentation. Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Kyle Walker <kwalker@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Stanislav Kozina <skozina@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by:
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Oleg Nesterov authored
task_will_free_mem() is wrong in many ways, and in particular the SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the coredumping without SIGNAL_GROUP_COREDUMP bit set. change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if other CLONE_VM processes can't react to SIGKILL. Fortunately, at least oom-kill case if fine; it kills all tasks sharing the same mm, so it should also kill the process which actually dumps the core. The change in prepare_signal() is not strictly necessary, it just ensures that the patch does not bring another subtle behavioural change. But it reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes. Signed-off-by:
Michal Hocko <mhocko@suse.com> Cc: Stanislav Kozina <skozina@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by:
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Oleg Nesterov authored
jffs2_garbage_collect_thread() does allow_signal(SIGCONT) for no reason, SIGCONT will wake a stopped task up even if it is ignored. Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Felipe Balbi <balbi@ti.com> Cc: Markus Pargmann <mpa@pengutronix.de> Signed-off-by:
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Oleg Nesterov authored
jffs2_garbage_collect_thread() can race with SIGCONT and sleep in TASK_STOPPED state after it was already sent. Add the new helper, kernel_signal_stop(), which does this correctly. Signed-off-by:
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Oleg Nesterov authored
1. Rename dequeue_signal_lock() to kernel_dequeue_signal(). This matches another "for kthreads only" kernel_sigaction() helper. 2. Remove the "tsk" and "mask" arguments, they are always current and current->blocked. And it is simply wrong if tsk != current. 3. We could also remove the 3rd "siginfo_t *info" arg but it looks potentially useful. However we can simplify the callers if we change kernel_dequeue_signal() to accept info => NULL. 4. Remove _irqsave, it is never called from atomic context. Signed-off-by:
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Oleg Nesterov authored
It is hardly possible to enumerate all problems with block_all_signals() and unblock_all_signals(). Just for example, 1. block_all_signals(SIGSTOP/etc) simply can't help if the caller is multithreaded. Another thread can dequeue the signal and force the group stop. 2. Even is the caller is single-threaded, it will "stop" anyway. It will not sleep, but it will spin in kernel space until SIGCONT or SIGKILL. And a lot more. In short, this interface doesn't work at all, at least the last 10+ years. Daniel said: Yeah the only times I played around with the DRM_LOCK stuff was when old drivers accidentally deadlocked - my impression is that the entire DRM_LOCK thing was never really tested properly ;-) Hence I'm all for purging where this leaks out of the drm subsystem. Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by:
Dave Airlie <airlied@redhat.com> Cc: Richard Weinberger <richard@nod.at> Signed-off-by:
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Ryusuke Konishi authored
Some false positive warnings are reported for powerpc build. The following warnings are reported in http://kisskb.ellerman.id.au/kisskb/buildresult/12519703/ CC fs/nilfs2/super.o fs/nilfs2/super.c: In function 'nilfs_resize_fs': fs/nilfs2/super.c:376:2: warning: 'blocknr' may be used uninitialized in this function [-Wuninitialized] fs/nilfs2/super.c:362:11: note: 'blocknr' was declared here CC fs/nilfs2/recovery.o fs/nilfs2/recovery.c: In function 'nilfs_salvage_orphan_logs': fs/nilfs2/recovery.c:631:21: warning: 'sum' may be used uninitialized in this function [-Wuninitialized] fs/nilfs2/recovery.c:585:32: note: 'sum' was declared here fs/nilfs2/recovery.c: In function 'nilfs_search_super_root': fs/nilfs2/recovery.c:873:11: warning: 'sum' may be used uninitialized in this function [-Wuninitialized] Another similar warning is reported in http://kisskb.ellerman.id.au/kisskb/buildresult/12520079/ CC fs/nilfs2/btree.o fs/nilfs2/btree.c: In function 'nilfs_btree_convert_and_insert': include/asm-generic/bitops/non-atomic.h:105:20: warning: 'bh' may be used uninitialized in this function [-Wuninitialized] fs/nilfs2/btree.c:1859:22: note: 'bh' was declared here This cleans out these warnings by forcing the variables to be initialized. Signed-off-by:
Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Reported-by:
Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by:
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Ryusuke Konishi authored
Fix the following build warnings: $ make W=1 [...] CC [M] fs/nilfs2/btree.o fs/nilfs2/btree.c: In function 'nilfs_btree_split': fs/nilfs2/btree.c:923:8: warning: variable 'newptr' set but not used [-Wunused-but-set-variable] __u64 newptr; ^ fs/nilfs2/btree.c:922:8: warning: variable 'newkey' set but not used [-Wunused-but-set-variable] __u64 newkey; ^ CC [M] fs/nilfs2/dat.o fs/nilfs2/dat.c: In function 'nilfs_dat_prepare_end': fs/nilfs2/dat.c:158:8: warning: variable 'start' set but not used [-Wunused-but-set-variable] __u64 start; ^ CC [M] fs/nilfs2/segment.o fs/nilfs2/segment.c: In function 'nilfs_segctor_do_immediate_flush': fs/nilfs2/segment.c:2433:6: warning: variable 'err' set but not used [-Wunused-but-set-variable] int err; ^ CC [M] fs/nilfs2/sufile.o fs/nilfs2/sufile.c: In function 'nilfs_sufile_alloc': fs/nilfs2/sufile.c:320:27: warning: variable 'ncleansegs' set but not used [-Wunused-but-set-variable] unsigned long nsegments, ncleansegs, nsus, cnt; ^ CC [M] fs/nilfs2/alloc.o fs/nilfs2/alloc.c: In function 'nilfs_palloc_prepare_alloc_entry': fs/nilfs2/alloc.c:478:38: warning: variable 'groups_per_desc_block' set but not used [-Wunused-but-set-variable] unsigned long n, entries_per_group, groups_per_desc_block; ^ Signed-off-by: -
Ryusuke Konishi authored
This adds header file "include/trace/events/nilfs2.h" to maintainer-ship of nilfs2 so that updates to the nilfs2 header file go to the mailing list of nilfs2. Signed-off-by:
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Hitoshi Mitake authored
This patch adds tracepoints for analyzing requests of reading and writing metadata files. The tracepoints cover every in-place mdt files (cpfile, sufile, and datfile). Example of tracing mdt_insert_new_block(): cp-14635 [000] ...1 30598.199309: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 155 cp-14635 [000] ...1 30598.199520: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 5 cp-14635 [000] ...1 30598.200828: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 253 Signed-off-by:Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp> Signed-off-by:
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Hitoshi Mitake authored
This patch adds tracepoints which would be useful for analyzing segment usage from a perspective of high level sufile manipulation (check, alloc, free). sufile is an important in-place updated metadata file, so analyzing the behavior would be useful for performance turning. example of usage (a case of allocation): $ sudo bin/tpoint nilfs2:nilfs2_segment_usage_allocated Tracing nilfs2:nilfs2_segment_usage_allocated. Ctrl-C to end. segctord-17800 [002] ...1 10671.867294: nilfs2_segment_usage_allocated: sufile = ffff880054f908a8 segnum = 2 segctord-17800 [002] ...1 10675.073477: nilfs2_segment_usage_allocated: sufile = ffff880054f908a8 segnum = 3 Signed-off-by: -
Hitoshi Mitake authored
This patch adds a tracepoint for transaction events of nilfs. With the tracepoint, these events can be tracked: begin, abort, commit, trylock, lock, and unlock. Basically, these events have corresponding functions e.g. begin event corresponds nilfs_transaction_begin(). The unlock event is an exception. It corresponds to the iteration in nilfs_transaction_lock(). Only one tracepoint is introcued: nilfs2_transaction_transition. The above events are distinguished with newly introduced enum. With this tracepoint, we can analyse a critical section of segment constructoin. Sample output by tpoint of perf-tools: cp-4457 [000] ...1 63.266220: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 1 flags = 9 state = BEGIN cp-4457 [000] ...1 63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT cp-4457 [000] ...1 63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT segctord-4371 [001] ...1 68.261196: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK segctord-4371 [001] ...1 68.261280: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = LOCK segctord-4371 [001] ...1 68.261877: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 1 flags = 10 state = BEGIN segctord-4371 [001] ...1 68.262116: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = COMMIT segctord-4371 [001] ...1 68.265032: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = UNLOCK segctord-4371 [001] ...1 132.376847: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK This patch also does trivial cleaning of comma usage in collection stage transition event for consistent coding style. Signed-off-by: -
Hitoshi Mitake authored
This patch adds a tracepoint for tracking stage transition of block collection in segment construction. With the tracepoint, we can analysis the behavior of segment construction in depth. It would be useful for bottleneck detection and debugging, etc. The tracepoint is created with the standard trace API of linux (like ext3, ext4, f2fs and btrfs). So we can analysis with existing tools easily. Of course, more detailed analysis will be possible if we can create nilfs specific analysis tools. Below is an example of event dump with Brendan Gregg's perf-tools (https://github.com/brendangregg/perf-tools). Time consumption between each stage can be obtained. $ sudo bin/tpoint nilfs2:nilfs2_collection_stage_transition Tracing nilfs2:nilfs2_collection_stage_transition. Ctrl-C to end. segctord-14875 [003] ...1 28311.067794: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_INIT segctord-14875 [003] ...1 28311.068139: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_GC segctord-14875 [003] ...1 28311.068139: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_FILE segctord-14875 [003] ...1 28311.068486: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_IFILE segctord-14875 [003] ...1 28311.068540: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_CPFILE segctord-14875 [003] ...1 28311.068561: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_SUFILE segctord-14875 [003] ...1 28311.068565: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_DAT segctord-14875 [003] ...1 28311.068573: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_SR segctord-14875 [003] ...1 28311.068574: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_DONE For capturing transition correctly, this patch adds wrappers for the member scnt of nilfs_cstage. With this change, every transition of the stage can produce trace event in a correct manner. Signed-off-by:
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Ryusuke Konishi authored
As a nilfs2 volume ages, the amount of available disk space decreases little by little due to bloat of DAT (disk address translation) metadata file. Even if we delete all files in a file system and free their block addresses from the DAT file through a garbage collection, empty DAT blocks are not freed. This fixes the issue by extending the deallocator of block addresses so that empty data blocks and empty bitmap blocks of DAT are deleted. The following comparison shows the effect of this patch. Each shows disk amount information of a nilfs2 volume that we cleaned out by deleting all files and running gc after having filled 90% of its capacity. Before: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 500105212 3022844 472072192 1% /test After: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 500105212 16380 475078656 1% /test Signed-off-by:
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Ryusuke Konishi authored
This adds delete functions for data blocks of metadata files using bitmap based allocator. nilfs_palloc_delete_entry_block() deletes an entry block (e.g. block storing dat entries), and nilfs_palloc_delete_bitmap_block() deletes a bitmap block, respectively. These helpers are intended to be used in the successive change on deallocator of block addresses ("nilfs2: free unused dat file blocks during garbage collection"). Signed-off-by: -
Ryusuke Konishi authored
This unfolds nilfs_palloc_group_is_in() helper function into nilfs_palloc_freev() function to simplify a range check and an index calculation repeatedy performed in a loop of the function. Signed-off-by:
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Ryusuke Konishi authored
The current implementation of nilfs_palloc_find_available_slot() function is overkill. The underlying bit search routine is well optimized, so this uses it more simply in nilfs_palloc_find_available_slot(). Signed-off-by:
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Ryusuke Konishi authored
In the bitmap based allocator implementation, nilfs_mdt_bgl_lock() helper is frequently used to get a spinlock protecting a target block group. This reduces its usage and simplifies arguments of some related functions by directly passing a pointer to the spinlock. Signed-off-by:
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Ryusuke Konishi authored
This uses nilfs_warning() to replace "printk(KERN_WARNING ...);" in the bitmap based allocator implementation of nilfs2. The warning messages are modified to include the device name and the inode number in each message. This makes it clear which metadata file of which device has output warnings such as "entry number xxxx already freed". Signed-off-by:
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Julia Lawall authored
Remove unneeded NULL test. The semantic patch that makes this change is as follows: (http://coccinelle.lip6.fr/) // <smpl> @@ expression x; @@ -if (x != NULL) \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x); // </smpl> Signed-off-by:
Julia Lawall <Julia.Lawall@lip6.fr> Signed-off-by:
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Joe Perches authored
Global and static variables don't need to be initialized to 0. There is already a test for this but the output message doesn't mention booleans initialized to false. Improve the output message and the test by adding various forms with possible specific integer types and possible multiple zeros. Miscellanea: o Use a variable to hold the possible 0 test Signed-off-by:
Joe Perches <joe@perches.com> Signed-off-by:
Shailendra Verma <shailendra.v@samsung.com> Tested-by:
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Joe Perches authored
Including BUG and stack dumps in commit logs makes checkpatch produce some false positive warning messages. checkpatch has multiple types of false positives: o Commit message lines > 75 chars o Stack dump address are mistaken for git commit IDs o Link: and Fixes: lines are allowed to be > 75 chars. o Fixes: style doesn't require ("<commit_description>") parentheses and double quotes like other uses of git commit ID and description. Fix these. Miscellanea: o Move the test for checking $commit_log_possible_stack_dump above the test for a long line commit message o Add test for hex address surrounded by square or angle brackets Signed-off-by:Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by:
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Andy Shevchenko authored
There is a classical off-by-one error in case when we try to place, for example, 1+1 bytes as hex in the buffer of size 6. The expected result is to get an output truncated, but in the reality we get 6 bytes filed followed by terminating NUL. Change the logic how we fill the output in case of byte dumping into limited space. This will follow the snprintf() behaviour by truncating output even on half bytes. Fixes: 114fc1af (hexdump: make it return number of bytes placed in buffer) Signed-off-by:
Aaro Koskinen <aaro.koskinen@nokia.com> Tested-by:
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Cody P Schafer authored
I noticed that commit a20135ff ("writeback: don't drain bdi_writeback_congested on bdi destruction") added a usage of rbtree_postorder_for_each_entry_safe() in mm/backing-dev.c which appears to try to rb_erase() elements from an rbtree while iterating over it using rbtree_postorder_for_each_entry_safe(). Doing this will cause random nodes to be missed by the iteration because rb_erase() may rebalance the tree, changing the ordering that we're trying to iterate over. The previous documentation for rbtree_postorder_for_each_entry_safe() wasn't clear that this wasn't allowed, it was taken from the docs for list_for_each_entry_safe(), where erasing isn't a problem due to list_del() not reordering. Explicitly warn developers about this potential pit-fall. Note that I haven't fixed the actual issue that (it appears) the commit referenced above introduced (not familiar enough with that code). In general (and in this case), the patterns to follow are: - switch to rb_first() + rb_erase(), don't use rbtree_postorder_for_each_entry_safe(). - keep the postorder iteration and don't rb_erase() at all. Instead just clear the fields of rb_node & cgwb_congested_tree as required by other users of those structures. [akpm@linux-foundation.org: tweak comments] Signed-off-by:
Cody P Schafer <dev@codyps.com> Cc: John de la Garza <john@jjdev.com> Cc: Michel Lespinasse <walken@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Oleg Nesterov authored
Change current_is_single_threaded() to use for_each_thread() rather than deprecated while_each_thread(). Signed-off-by:
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Rasmus Villemoes authored
Sometimes kobject_set_name_vargs is called with a format string conaining no %, or a format string of precisely "%s", where the single vararg happens to point to .rodata. kvasprintf_const detects these cases for us and returns a copy of that pointer instead of duplicating the string, thus saving some run-time memory. Otherwise, it falls back to kvasprintf. We just need to always deallocate ->name using kfree_const. Unfortunately, the dance we need to do to perform the '/' -> '!' sanitization makes the resulting code rather ugly. I instrumented kstrdup_const to provide some statistics on the memory saved, and for me this gave an additional ~14KB after boot (306KB was already saved; this patch bumped that to 320KB). I have KMALLOC_SHIFT_LOW==3, and since 80% of the kvasprintf_const hits were satisfied by an 8-byte allocation, the 14K would roughly be quadrupled when KMALLOC_SHIFT_LOW==5. Whether these numbers are sufficient to justify the ugliness I'll leave to others to decide. Signed-off-by:
Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Greg KH <greg@kroah.com> Signed-off-by:
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Rasmus Villemoes authored
This adds kvasprintf_const which tries to use kstrdup_const if possible: If the format string contains no % characters, or if the format string is exactly "%s", we delegate to kstrdup_const. Otherwise, we fall back to kvasprintf. Just as for kstrdup_const, the main motivation is to save memory by reusing .rodata when possible. The return value should be freed by kfree_const, just like for kstrdup_const. There is deliberately no kasprintf_const: In the vast majority of cases, the format string argument is a literal, so one can determine statically whether one could instead use kstrdup_const directly (which would also require one to change all corresponding kfree calls to kfree_const). Signed-off-by:
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Dmitry Vyukov authored
llist_del_first reads entry->next, but it did not acquire visibility over the entry node. As the result it can get a stale value of entry->next (e.g. NULL or whatever garbage was there before the appending thread wrote correct value). And then commit that value as llist head with cmpxchg. That will corrupt llist. Note there is a control-dependency between read of head->first and read of entry->next, but it does not make the code correct. Kernel memory model unambiguously says: "A load-load control dependency requires a full read memory barrier". Use smp_load_acquire to acquire visibility over the entry node. The data race was found with KernelThreadSanitizer (KTSAN). Here is an example of KTSAN report: ThreadSanitizer: data-race in llist_del_first Read of size 1 by thread T389 (K2630, CPU0): [<ffffffff8156b8a9>] llist_del_first+0x39/0x70 lib/llist.c:74 [< inlined >] tty_buffer_alloc drivers/tty/tty_buffer.c:181 [<ffffffff81664af4>] __tty_buffer_request_room+0xb4/0x250 drivers/tty/tty_buffer.c:292 [<ffffffff81664e6c>] tty_insert_flip_string_fixed_flag+0x6c/0x150 drivers/tty/tty_buffer.c:337 [< inlined >] tty_insert_flip_string include/linux/tty_flip.h:35 [<ffffffff81667422>] pty_write+0x72/0xc0 drivers/tty/pty.c:110 [< inlined >] process_output_block drivers/tty/n_tty.c:611 [<ffffffff8165c016>] n_tty_write+0x346/0x7f0 drivers/tty/n_tty.c:2401 [< inlined >] do_tty_write drivers/tty/tty_io.c:1159 [<ffffffff816568df>] tty_write+0x21f/0x3f0 drivers/tty/tty_io.c:1245 [<ffffffff8125f00f>] __vfs_write+0x5f/0x1f0 fs/read_write.c:489 [<ffffffff8125ff8f>] vfs_write+0xef/0x280 fs/read_write.c:538 [< inlined >] SYSC_write fs/read_write.c:585 [<ffffffff81261390>] SyS_write+0x70/0xe0 fs/read_write.c:577 [<ffffffff81ee862e>] entry_SYSCALL_64_fastpath+0x12/0x71 arch/x86/entry/entry_64.S:186 Previous write of size 8 by thread T226 (K761, CPU0): [<ffffffff8156b832>] llist_add_batch+0x32/0x70 lib/llist.c:44 (discriminator 16) [< inlined >] llist_add include/linux/llist.h:180 [<ffffffff816649fc>] tty_buffer_free+0x6c/0xb0 drivers/tty/tty_buffer.c:221 [<ffffffff816651e7>] flush_to_ldisc+0x107/0x300 drivers/tty/tty_buffer.c:514 [<ffffffff810b20ee>] process_one_work+0x47e/0x930 kernel/workqueue.c:2036 [<ffffffff810b2650>] worker_thread+0xb0/0x900 kernel/workqueue.c:2170 [<ffffffff810bbe20>] kthread+0x150/0x170 kernel/kthread.c:209 [<ffffffff81ee8a1f>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:526 Signed-off-by:
Dmitry Vyukov <dvyukov@google.com> Reviewed-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Huang Ying <ying.huang@intel.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Signed-off-by:
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Vitaly Kuznetsov authored
Add a couple of simple tests for string_get_size(). The last one will hang the kernel without the 'lib/string_helpers.c: fix infinite loop in string_get_size()' fix. Signed-off-by:
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Alexander Kuleshov authored
<linux/bitops.h> provides rol32() inline function, let's use already predefined function instead of direct expression. Signed-off-by:
Alexander Kuleshov <kuleshovmail@gmail.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:
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