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* binfmt_misc: add comments & debug logsMike Frysinger2014-12-101-15/+121
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When trying to develop a custom format handler, the errors returned all effectively get bucketed as EINVAL with no kernel messages. The other errors (ENOMEM/EFAULT) are internal/obvious and basic. Thus any time a bad handler is rejected, the developer has to walk the dense code and try to guess where it went wrong. Needing to dive into kernel code is itself a fairly high barrier for a lot of people. To improve this situation, let's deploy extensive pr_debug markers at logical parse points, and add comments to the dense parsing logic. It let's you see exactly where the parsing aborts, the string the kernel received (useful when dealing with shell code), how it translated the buffers to binary data, and how it will apply the mask at runtime. Some example output: $ echo ':qemu-foo:M::\x7fELF\xAD\xAD\x01\x00:\xff\xff\xff\xff\xff\x00\xff\x00:/usr/bin/qemu-foo:POC' > register $ dmesg binfmt_misc: register: received 92 bytes binfmt_misc: register: delim: 0x3a {:} binfmt_misc: register: name: {qemu-foo} binfmt_misc: register: type: M (magic) binfmt_misc: register: offset: 0x0 binfmt_misc: register: magic[raw]: 5c 78 37 66 45 4c 46 5c 78 41 44 5c 78 41 44 5c \x7fELF\xAD\xAD\ binfmt_misc: register: magic[raw]: 78 30 31 5c 78 30 30 00 x01\x00. binfmt_misc: register: mask[raw]: 5c 78 66 66 5c 78 66 66 5c 78 66 66 5c 78 66 66 \xff\xff\xff\xff binfmt_misc: register: mask[raw]: 5c 78 66 66 5c 78 30 30 5c 78 66 66 5c 78 30 30 \xff\x00\xff\x00 binfmt_misc: register: mask[raw]: 00 . binfmt_misc: register: magic/mask length: 8 binfmt_misc: register: magic[decoded]: 7f 45 4c 46 ad ad 01 00 .ELF.... binfmt_misc: register: mask[decoded]: ff ff ff ff ff 00 ff 00 ........ binfmt_misc: register: magic[masked]: 7f 45 4c 46 ad 00 01 00 .ELF.... binfmt_misc: register: interpreter: {/usr/bin/qemu-foo} binfmt_misc: register: flag: P (preserve argv0) binfmt_misc: register: flag: O (open binary) binfmt_misc: register: flag: C (preserve creds) The [raw] lines show us exactly what was received from userspace. The lines after that show us how the kernel has decoded things. Signed-off-by: Mike Frysinger <vapier@gentoo.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add ability to --fix (coalesce) string fragments on multiple linesJoe Perches2014-12-101-46/+69
| | | | | | | | | | | | | | | | | | | Add --fix option to coalesce string fragments. This does not coalesce string fragments that have newline terminations or are otherwise exempted. Other miscellanea: o move all the string tests together. o fix get_quoted_string function for tab characters o fix concatination typo Signed-off-by: Joe Perches <joe@perches.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add --strict "pointer comparison to NULL" testJoe Perches2014-12-101-0/+14
| | | | | | | | | | | | | | | | It seems there are more and more uses of "if (!ptr)" in preference to "if (ptr == NULL)" so add a --strict test to emit a message when using the latter form. This also finds (ptr != NULL). Fix it too if desired. Signed-off-by: Joe Perches <joe@perches.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Greg KH <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add test for consecutive string fragmentsJoe Perches2014-12-101-0/+6
| | | | | | | | | | | | | | | | Emit a warning when single line string coalescing occurs. Code that uses compiler string concatenation on a single line like: printk("foo" "bar"); is generally better to read concatenated like: printk("foobar"); Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add --strict preference for #defines using BIT(foo)Joe Perches2014-12-101-0/+11
| | | | | | | | | | | | | Using BIT(foo) and BIT_ULL(bar) is more common now. Suggest using these macros over #defines with 1<<value. Add a --fix option too. Signed-off-by: Joe Perches <joe@perches.com> Cc: David Miller <davem@davemloft.net> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: allow certain SI units with three charactersJulius Werner2014-12-101-1/+3
| | | | | | | | | | | | | | | | | | Checkpatch flags CamelCase identifiers in strict mode, but it has a feature to ignore parts with only two characters to allow for SI units like mV or uA. Unfortunately, not all SI units fit in two characters, and not all are lower case followed by upper case. This patch adds hardcoded detection for frequency and 1024-based size units (Hz/KHz/MHz/GHz/THz and KiB/MiB/GiB/TiB), since allowing any three character combinations might be too lenient. The list can later be expanded as needed. Signed-off-by: Julius Werner <jwerner@chromium.org> Acked-by: Joe Perches <joe@perches.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: Add --strict test for function pointer calling styleJoe Perches2014-12-101-3/+21
| | | | | | | | | | | | | | | | | Peter Hurley wrote: The use of older function ptr calling style, (*fn)(), makes static analysis more error-prone; replace with modern fn() style. So make checkpatch emit a --strict test for that condition. Update the unnecessary parentheses test for dereferencing objects at the same time and create a $fix mechanism too. Signed-off-by: Joe Perches <joe@perches.com> Cc: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: reduce MAINTAINERS update message frequencyJoe Perches2014-12-101-0/+6
| | | | | | | | | | | | When files are being added/moved/deleted and a patch contains an update to the MAINTAINERS file, assume it's to update the MAINTAINERS file correctly and do not emit the "does MAINTAINERS need updating?" message. Reported by many people. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: try to avoid mask and shift errorsJoe Perches2014-12-101-0/+8
| | | | | | | | | | | | Shift has a higher precedence that mask so warn when a mask then shift operation is done without parentheses around the mask. This test works well for a right shift, but the left shift is pretty commonly done correctly so only warn on the right shift. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: fix use via symlink, make missing spelling file non-fatalJoe Perches2014-12-101-17/+21
| | | | | | | | | | | | | | | | | | Commit 66b47b4a9dad ("checkpatch: look for common misspellings") made it difficult to use checkpatch via a symlink. Fix that and make a missing spelling.txt file non-fatal. Emit a warning when the spelling.txt file can not be opened. Reference: http://xkcd.com/1172/ Signed-off-by: Joe Perches <joe@perches.com> Reported-by: Jani Nikula <jani.nikula@intel.com> Tested-by: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: improve warning message for "needless if" caseFabio Estevam2014-12-101-1/+1
| | | | | | | | | | | Add an 'and' to the sentence so that it looks better: WARNING: debugfs_remove(NULL) is safe and this check is probably not required Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: improve test for no space after castJoe Perches2014-12-101-1/+2
| | | | | | | | | sizeof(foo) is not a cast, allow a space after it. Signed-off-by: Joe Perches <joe@perches.com> Tested-by: Kalle Valo <kvalo@qca.qualcomm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add error on use of attribute((weak)) or __weak declarationsJoe Perches2014-12-101-0/+9
| | | | | | | | | | | | Using weak declarations can have unintended link defects. The __weak on the declaration causes non-weak definitions to become weak. Emit an error on its use. Signed-off-by: Joe Perches <joe@perches.com> Reported-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* checkpatch: add an error test for no space before commaJoe Perches2014-12-101-2/+21
| | | | | | | | | | | | | | | | Using code like: int foo , bar; is not preferred to: int foo, bar; so emit an error on this style. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/lcm.c: lcm(n,0)=lcm(0,n) is 0, not nRasmus Villemoes2014-12-101-4/+2
| | | | | | | | | Return the mathematically correct answer when an argument is 0. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib/lcm.c: ensure correct result whenever it fitsRasmus Villemoes2014-12-101-1/+1
| | | | | | | | | | | Ensure that lcm(a,b) returns the mathematically correct result, provided it fits in an unsigned long. The current version returns garbage if a*b overflows, even if the final result would fit. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* MAINTAINERS: update ivtv mailing lists as subscriber-onlyJoe Perches2014-12-101-2/+2
| | | | | | | | | | Mark these as subscriber-only mailing lists. Signed-off-by: Joe Perches <joe@perches.com> Cc: Andy Walls <awalls@md.metrocast.net> Cc: Mauro Carvalho Chehab <mchehab@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: drop logbuf_cpu volatile qualifierAlex Elder2014-12-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pranith Kumar posted a patch in which removed the "volatile" qualifier for the "logbuf_cpu" variable in vprintk_emit(). https://lkml.org/lkml/2014/11/13/894 In his patch, he used ACCESS_ONCE() for all references to that symbol to provide whatever protection was intended. There was some discussion that followed, and in the end Steven Rostedt concluded that not only was "volatile" not needed, neither was it required to use ACCESS_ONCE(). I offered an elaborate description that concluded Steven was right, and Pranith asked me to submit an alternative patch. And this is it. The basic reason "volatile" is not needed is that "logbuf_cpu" has static storage duration, and vprintk_emit() is an exported interface. This means that the value of logbuf_cpu must be read from memory the first time it is used in a particular call of vprintk_emit(). The variable's value is read only once in that function, when it's read it'll be the copy from memory (or cache). In addition, the value of "logbuf_cpu" is only ever written under protection of a spinlock. So the value that is read is the "real" value (and not an out-of-date cached one). If its value is not UINT_MAX, it is the current CPU's processor id, and it will have been last written by the running CPU. Signed-off-by: Alex Elder <elder@linaro.org> Reported-by: Pranith Kumar <bobby.prani@gmail.com> Suggested-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: add and use LOGLEVEL_<level> defines for KERN_<LEVEL> equivalentsJoe Perches2014-12-104-18/+29
| | | | | | | | | | Use #defines instead of magic values. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jason Baron <jbaron@akamai.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tile: use pr_warn instead of pr_warningJoe Perches2014-12-101-18/+15
| | | | | | | | | | | Use the more common pr_warn. Coalesce formats, realign arguments. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tile: neaten early_printk usesJoe Perches2014-12-101-7/+5
| | | | | | | | | Coalesce the formats and align arguments. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: remove used-once early_vprintkJoe Perches2014-12-103-18/+21
| | | | | | | | | | | | | | | | | Eliminate the unlikely possibility of message interleaving for early_printk/early_vprintk use. early_vprintk can be done via the %pV extension so remove this unnecessary function and change early_printk to have the equivalent vprintk code. All uses of early_printk already end with a newline so also remove the unnecessary newline from the early_printk function. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: add panic_on_warnPrarit Bhargava2014-12-108-14/+61
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There have been several times where I have had to rebuild a kernel to cause a panic when hitting a WARN() in the code in order to get a crash dump from a system. Sometimes this is easy to do, other times (such as in the case of a remote admin) it is not trivial to send new images to the user. A much easier method would be a switch to change the WARN() over to a panic. This makes debugging easier in that I can now test the actual image the WARN() was seen on and I do not have to engage in remote debugging. This patch adds a panic_on_warn kernel parameter and /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() path. The function will still print out the location of the warning. An example of the panic_on_warn output: The first line below is from the WARN_ON() to output the WARN_ON()'s location. After that the panic() output is displayed. WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]() Kernel panic - not syncing: panic_on_warn set ... CPU: 30 PID: 11698 Comm: insmod Tainted: G W OE 3.17.0+ #57 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190 0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df Call Trace: [<ffffffff81665190>] dump_stack+0x46/0x58 [<ffffffff8165e2ec>] panic+0xd0/0x204 [<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module] [<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0 [<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module] [<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20 [<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module] [<ffffffff81002144>] do_one_initcall+0xd4/0x210 [<ffffffff811b52c2>] ? __vunmap+0xc2/0x110 [<ffffffff810f8889>] load_module+0x16a9/0x1b30 [<ffffffff810f3d30>] ? store_uevent+0x70/0x70 [<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180 [<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0 [<ffffffff8166cf29>] system_call_fastpath+0x12/0x17 Successfully tested by me. hpa said: There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Fabian Frederick <fabf@skynet.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* include/linux/file.h: remove get_unused_fd() macroYann Droneaud2014-12-101-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | Macro get_unused_fd() is used to allocate a file descriptor with default flags. Those default flags (0) don't enable close-on-exec. This can be seen as an unsafe default: in most case close-on-exec should be enabled to not leak file descriptor across exec(). It would be better to have a "safer" default set of flags, eg. O_CLOEXEC must be used to enable close-on-exec. Instead this patch removes get_unused_fd() so that out of tree modules won't be affect by a runtime behavor change which might introduce other kind of bugs: it's better to catch the change at build time, making it easier to fix. Removing the macro will also promote use of get_unused_fd_flags() (or anon_inode_getfd()) with flags provided by userspace. Or, if flags cannot be given by userspace, with flags set to O_CLOEXEC by default. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/file.c: replace get_unused_fd() with get_unused_fd_flags(0)Yann Droneaud2014-12-101-1/+1
| | | | | | | | | | | | | | This patch replaces calls to get_unused_fd() with equivalent call to get_unused_fd_flags(0) to preserve current behavor for existing code. In a further patch, get_unused_fd() will be removed so that new code start using get_unused_fd_flags(), with the hope O_CLOEXEC could be used, either by default or choosen by userspace. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* binfmt_misc: replace get_unused_fd() with get_unused_fd_flags(0)Yann Droneaud2014-12-101-1/+1
| | | | | | | | | | | | | | This patch replaces calls to get_unused_fd() with equivalent call to get_unused_fd_flags(0) to preserve current behavor for existing code. In a further patch, get_unused_fd() will be removed so that new code start using get_unused_fd_flags(), with the hope O_CLOEXEC could be used, either by default or choosen by userspace. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ppc/cell: replace get_unused_fd() with get_unused_fd_flags(0)Yann Droneaud2014-12-101-2/+2
| | | | | | | | | | | | | | This patch replaces calls to get_unused_fd() with equivalent call to get_unused_fd_flags(0) to preserve current behavor for existing code. In a further patch, get_unused_fd() will be removed so that new code start using get_unused_fd_flags(), with the hope O_CLOEXEC could be used, either by default or choosen by userspace. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ia64: replace get_unused_fd() with get_unused_fd_flags(0)Yann Droneaud2014-12-101-1/+1
| | | | | | | | | | | | | | This patch replaces calls to get_unused_fd() with equivalent call to get_unused_fd_flags(0) to preserve current behavor for existing code. In a further patch, get_unused_fd() will be removed so that new code start using get_unused_fd_flags(), with the hope O_CLOEXEC could be used, either by default or choosen by userspace. Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exit: ptrace: shift "reap dead" code from exit_ptrace() to ↵Oleg Nesterov2014-12-103-27/+8
| | | | | | | | | | | | | | | | | | | | | | forget_original_parent() Now that forget_original_parent() uses ->ptrace_entry for EXIT_DEAD tasks, we can simply pass "dead_children" list to exit_ptrace() and remove another release_task() loop. Plus this way we do not need to drop and reacquire tasklist_lock. Also shift the list_empty(ptraced) check, if we want this optimization it makes sense to eliminate the function call altogether. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exit: reparent: cleanup the usage of reparent_leader()Oleg Nesterov2014-12-101-13/+9
| | | | | | | | | | | | | | | | | | | | 1. Now that reparent_leader() doesn't abuse ->sibling we can shift list_move_tail() from reparent_leader() to forget_original_parent() and turn it into a single list_splice_tail_init(). This also makes BUG_ON(!list_empty()) and list_for_each_entry_safe() unnecessary. 2. This also allows to shift the same_thread_group() check, it looks a bit more clear in the caller. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exit: reparent: cleanup the changing of ->parentOleg Nesterov2014-12-101-8/+5
| | | | | | | | | | | | | | | | | | | | | | | 1. Cosmetic, but "if (t->parent == father)" looks a bit confusing. We need to change t->parent if and only if t is not traced. 2. If we actually want this BUG_ON() to ensure that parent/ptrace match each other, then we should also take ptrace_reparented() case into account too. 3. Change this code to use for_each_thread() instead of deprecated while_each_thread(). [dan.carpenter@oracle.com: silence a bogus static checker warning] Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exit: reparent: use ->ptrace_entry rather than ->sibling for EXIT_DEAD tasksOleg Nesterov2014-12-101-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | reparent_leader() reuses ->sibling as a list node to add an EXIT_DEAD task into dead_children list we are going to release. This obviously removes the dead task from its real_parent->children list and this is even good; the parent can do nothing with the EXIT_DEAD reparented zombie, it only makes do_wait() slower. But, this also means that it can not be reparented once again, so if its new parent dies too nobody will update ->parent/real_parent, they can point to the freed memory even before release_task() we are going to call, this breaks the code which relies on pid_alive() to access ->real_parent/parent. Fortunately this is mostly theoretical, this can only happen if init or PR_SET_CHILD_SUBREAPER process ignores SIGCHLD and the new parent sub-thread exits right after we drop tasklist_lock. Change this code to use ->ptrace_entry instead, we know that the child is not traced so nobody can ever use this member. This also allows to unify this logic with exit_ptrace(), see the next changes. Note: we really need to change release_task() to nullify real_parent/ parent/group_leader pointers, but we need to change the current users first somehow. And it would be better to reap this zombie immediately but release_task_locked() we need is complicated by proc_flush_task(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched_show_task: fix unsafe usage of ->real_parentOleg Nesterov2014-12-101-1/+3
| | | | | | | | | | | | | | | | | | | rcu_read_lock() can not protect p->real_parent if release_task(p) was already called, change sched_show_task() to check pis_alive() like other users do. Note: we need some helpers to cleanup the code like this. And it seems that that the usage of cpu_curr(cpu) in dump_cpu_task() is not safe too. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: task_state: ptrace_parent() doesn't need pid_alive() checkOleg Nesterov2014-12-101-7/+6
| | | | | | | | | | | | | | | | | | | p->ptrace != 0 means that release_task(p) was not called, so pid_alive() buys nothing and we can remove this check. Other callers already use it directly without additional checks. Note: with or without this patch ptrace_parent() can return the pointer to the freed task, this will be explained/fixed later. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: task_state: move the main seq_printf() outside of rcu_read_lock()Oleg Nesterov2014-12-101-6/+6
| | | | | | | | | | | | | | | | | task_state() does seq_printf() under rcu_read_lock(), but this is only needed for task_tgid_nr_ns() and task_numa_group_id(). We can calculate tgid/ngid and drop rcu lock. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: task_state: deuglify the max_fds calculationOleg Nesterov2014-12-101-12/+11
| | | | | | | | | | | | | | | | | | 1. The usage of fdt looks very ugly, it can't be NULL if ->files is not NULL. We can use "unsigned int max_fds" instead. 2. This also allows to move seq_printf(max_fds) outside of task_lock() and join it with the previous seq_printf(). See also the next patch. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: task_state: read cred->group_info outside of task_lock()Oleg Nesterov2014-12-101-2/+1
| | | | | | | | | | | | | | | | | task_state() reads cred->group_info under task_lock() because a long ago it was task_struct->group_info and it was actually protected by task->alloc_lock. Today this task_unlock() after rcu_read_unlock() just adds the confusion, move task_unlock() up. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/proc.c: use rb_entry_safe() instead of rb_entry()Nicolas Dichtel2014-12-101-12/+4
| | | | | | | | Better to use existing macro that rewriting them. Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* procfs: fix error handling of proc_register()Debabrata Banerjee2014-12-101-1/+8
| | | | | | | | | | proc_register() error paths are leaking inodes and directory refcounts. Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/proc: use a rb tree for the directory entriesNicolas Dichtel2014-12-104-64/+113
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a lot of netdevices are created, one of the bottleneck is the creation of proc entries. This serie aims to accelerate this part. The current implementation for the directories in /proc is using a single linked list. This is slow when handling directories with large numbers of entries (eg netdevice-related entries when lots of tunnels are opened). This patch replaces this linked list by a red-black tree. Here are some numbers: dummy30000.batch contains 30 000 times 'link add type dummy'. Before the patch: $ time ip -b dummy30000.batch real 2m31.950s user 0m0.440s sys 2m21.440s $ time rmmod dummy real 1m35.764s user 0m0.000s sys 1m24.088s After the patch: $ time ip -b dummy30000.batch real 2m0.874s user 0m0.448s sys 1m49.720s $ time rmmod dummy real 1m13.988s user 0m0.000s sys 1m1.008s The idea of improving this part was suggested by Thierry Herbelot. [akpm@linux-foundation.org: initialise proc_root.subdir at compile time] Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Acked-by: David S. Miller <davem@davemloft.net> Cc: Thierry Herbelot <thierry.herbelot@6wind.com>. Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move page->mem_cgroup bad page handling into generic codeJohannes Weiner2014-12-105-49/+12
| | | | | | | | | | | | | | | | Now that the external page_cgroup data structure and its lookup is gone, let the generic bad_page() check for page->mem_cgroup sanity. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: David S. Miller <davem@davemloft.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Tejun Heo <tj@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: page_cgroup: rename file to mm/swap_cgroup.cJohannes Weiner2014-12-107-14/+13
| | | | | | | | | | | | | | | | | | Now that the external page_cgroup data structure and its lookup is gone, the only code remaining in there is swap slot accounting. Rename it and move the conditional compilation into mm/Makefile. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Tejun Heo <tj@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: embed the memcg pointer directly into struct pageJohannes Weiner2014-12-109-487/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Memory cgroups used to have 5 per-page pointers. To allow users to disable that amount of overhead during runtime, those pointers were allocated in a separate array, with a translation layer between them and struct page. There is now only one page pointer remaining: the memcg pointer, that indicates which cgroup the page is associated with when charged. The complexity of runtime allocation and the runtime translation overhead is no longer justified to save that *potential* 0.19% of memory. With CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding after the page->private member and doesn't even increase struct page, and then this patch actually saves space. Remaining users that care can still compile their kernels without CONFIG_MEMCG. text data bss dec hex filename 8828345 1725264 983040 11536649 b00909 vmlinux.old 8827425 1725264 966656 11519345 afc571 vmlinux.new [mhocko@suse.cz: update Documentation/cgroups/memory.txt] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Tejun Heo <tj@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcontrol: remove stale page_cgroup_lock commentJohannes Weiner2014-12-101-4/+0
| | | | | | | | | There is no cgroup-specific page lock anymore. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/frontswap.c: fix the condition in BUG_ONLi Haifeng2014-12-101-1/+1
| | | | | | | | | | The largest index of swap device is MAX_SWAPFILES-1. So the type should be less than MAX_SWAPFILES. Signed-off-by: Haifeng Li <omycle@gmail.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix a spelling mistakeWei Yuan2014-12-101-1/+1
| | | | | | | Signed-off-by Wei Yuan <weiyuan.wei@huawei.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: fix __unmap_hugepage_range()Hillf Danton2014-12-101-1/+3
| | | | | | | | | | | First, after flushing TLB, we have no need to scan pte from start again. Second, before bail out loop, the address is forwarded one step. Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, memcg: fix potential undefined behaviour in page stat accountingMichal Hocko2014-12-104-11/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit d7365e783edb ("mm: memcontrol: fix missed end-writeback page accounting") mem_cgroup_end_page_stat consumes locked and flags variables directly rather than via pointers which might trigger C undefined behavior as those variables are initialized only in the slow path of mem_cgroup_begin_page_stat. Although mem_cgroup_end_page_stat handles parameters correctly and touches them only when they hold a sensible value it is caller which loads a potentially uninitialized value which then might allow compiler to do crazy things. I haven't seen any warning from gcc and it seems that the current version (4.9) doesn't exploit this type undefined behavior but Sasha has reported the following: UBSan: Undefined behaviour in mm/rmap.c:1084:2 load of value 255 is not a valid value for type '_Bool' CPU: 4 PID: 8304 Comm: rngd Not tainted 3.18.0-rc2-next-20141029-sasha-00039-g77ed13d-dirty #1427 Call Trace: dump_stack (lib/dump_stack.c:52) ubsan_epilogue (lib/ubsan.c:159) __ubsan_handle_load_invalid_value (lib/ubsan.c:482) page_remove_rmap (mm/rmap.c:1084 mm/rmap.c:1096) unmap_page_range (./arch/x86/include/asm/atomic.h:27 include/linux/mm.h:463 mm/memory.c:1146 mm/memory.c:1258 mm/memory.c:1279 mm/memory.c:1303) unmap_single_vma (mm/memory.c:1348) unmap_vmas (mm/memory.c:1377 (discriminator 3)) exit_mmap (mm/mmap.c:2837) mmput (kernel/fork.c:659) do_exit (./arch/x86/include/asm/thread_info.h:168 kernel/exit.c:462 kernel/exit.c:747) do_group_exit (include/linux/sched.h:775 kernel/exit.c:873) SyS_exit_group (kernel/exit.c:901) tracesys_phase2 (arch/x86/kernel/entry_64.S:529) Fix this by using pointer parameters for both locked and flags and be more robust for future compiler changes even though the current code is implemented correctly. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix huge zero page accounting in smaps reportKirill A. Shutemov2014-12-105-36/+82
| | | | | | | | | | | | | | | | | | | | | | | As a small zero page, huge zero page should not be accounted in smaps report as normal page. For small pages we rely on vm_normal_page() to filter out zero page, but vm_normal_page() is not designed to handle pmds. We only get here due hackish cast pmd to pte in smaps_pte_range() -- pte and pmd format is not necessary compatible on each and every architecture. Let's add separate codepath to handle pmds. follow_trans_huge_pmd() will detect huge zero page for us. We would need pmd_dirty() helper to do this properly. The patch adds it to THP-enabled architectures which don't yet have one. [akpm@linux-foundation.org: use do_div to fix 32-bit build] Signed-off-by: "Kirill A. Shutemov" <kirill@shutemov.name> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Tested-by: Fengwei Yin <yfw.kernel@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcontrol: drop bogus RCU locking from mem_cgroup_same_or_subtree()Johannes Weiner2014-12-103-52/+24
| | | | | | | | | | | | | | | None of the mem_cgroup_same_or_subtree() callers actually require it to take the RCU lock, either because they hold it themselves or they have css references. Remove it. To make the API change clear, rename the leftover helper to mem_cgroup_is_descendant() to match cgroup_is_descendant(). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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