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* fs: prevent out-of-bounds array speculation when closing a file descriptorTheodore Ts'o2023-03-171-0/+1
| | | | | | | | | commit 609d54441493c99f21c1823dfd66fa7f4c512ff4 upstream. Google-Bug-Id: 114199369 Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fget: clarify and improve __fget_files() implementationLinus Torvalds2022-03-021-16/+57
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit e386dfc56f837da66d00a078e5314bc8382fab83 upstream. Commit 054aa8d439b9 ("fget: check that the fd still exists after getting a ref to it") fixed a race with getting a reference to a file just as it was being closed. It was a fairly minimal patch, and I didn't think re-checking the file pointer lookup would be a measurable overhead, since it was all right there and cached. But I was wrong, as pointed out by the kernel test robot. The 'poll2' case of the will-it-scale.per_thread_ops benchmark regressed quite noticeably. Admittedly it seems to be a very artificial test: doing "poll()" system calls on regular files in a very tight loop in multiple threads. That means that basically all the time is spent just looking up file descriptors without ever doing anything useful with them (not that doing 'poll()' on a regular file is useful to begin with). And as a result it shows the extra "re-check fd" cost as a sore thumb. Happily, the regression is fixable by just writing the code to loook up the fd to be better and clearer. There's still a cost to verify the file pointer, but now it's basically in the noise even for that benchmark that does nothing else - and the code is more understandable and has better comments too. [ Side note: this patch is also a classic case of one that looks very messy with the default greedy Myers diff - it's much more legible with either the patience of histogram diff algorithm ] Link: https://lore.kernel.org/lkml/20211210053743.GA36420@xsang-OptiPlex-9020/ Link: https://lore.kernel.org/lkml/20211213083154.GA20853@linux.intel.com/ Reported-by: kernel test robot <oliver.sang@intel.com> Tested-by: Carel Si <beibei.si@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Baokun Li <libaokun1@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fget: check that the fd still exists after getting a ref to itLinus Torvalds2021-12-081-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 054aa8d439b9185d4f5eb9a90282d1ce74772969 upstream. Jann Horn points out that there is another possible race wrt Unix domain socket garbage collection, somewhat reminiscent of the one fixed in commit cbcf01128d0a ("af_unix: fix garbage collect vs MSG_PEEK"). See the extended comment about the garbage collection requirements added to unix_peek_fds() by that commit for details. The race comes from how we can locklessly look up a file descriptor just as it is in the process of being closed, and with the right artificial timing (Jann added a few strategic 'mdelay(500)' calls to do that), the Unix domain socket garbage collector could see the reference count decrement of the close() happen before fget() took its reference to the file and the file was attached onto a new file descriptor. This is all (intentionally) correct on the 'struct file *' side, with RCU lookups and lockless reference counting very much part of the design. Getting that reference count out of order isn't a problem per se. But the garbage collector can get confused by seeing this situation of having seen a file not having any remaining external references and then seeing it being attached to an fd. In commit cbcf01128d0a ("af_unix: fix garbage collect vs MSG_PEEK") the fix was to serialize the file descriptor install with the garbage collector by taking and releasing the unix_gc_lock. That's not really an option here, but since this all happens when we are in the process of looking up a file descriptor, we can instead simply just re-check that the file hasn't been closed in the meantime, and just re-do the lookup if we raced with a concurrent close() of the same file descriptor. Reported-and-tested-by: Jann Horn <jannh@google.com> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fs: add fget_many() and fput_many()Jens Axboe2021-12-081-5/+10
| | | | | | | | | | | | | | | | | | commit 091141a42e15fe47ada737f3996b317072afcefb upstream. Some uses cases repeatedly get and put references to the same file, but the only exposed interface is doing these one at the time. As each of these entail an atomic inc or dec on a shared structure, that cost can add up. Add fget_many(), which works just like fget(), except it takes an argument for how many references to get on the file. Ditto fput_many(), which can drop an arbitrary number of references to a file. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fix multiplication overflow in copy_fdtable()Al Viro2020-05-271-1/+1
| | | | | | | | | | | | | | | | [ Upstream commit 4e89b7210403fa4a8acafe7c602b6212b7af6c3b ] cpy and set really should be size_t; we won't get an overflow on that, since sysctl_nr_open can't be set above ~(size_t)0 / sizeof(void *), so nr that would've managed to overflow size_t on that multiplication won't get anywhere near copy_fdtable() - we'll fail with EMFILE before that. Cc: stable@kernel.org # v2.6.25+ Fixes: 9cfe015aa424 (get rid of NR_OPEN and introduce a sysctl_nr_open) Reported-by: Thiago Macieira <thiago.macieira@intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Sasha Levin <sashal@kernel.org>
* fs/file.c: initialize init_files.resize_waitShuriyc Chu2019-04-051-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 5704a06810682683355624923547b41540e2801a ] (Taken from https://bugzilla.kernel.org/show_bug.cgi?id=200647) 'get_unused_fd_flags' in kthread cause kernel crash. It works fine on 4.1, but causes crash after get 64 fds. It also cause crash on ubuntu1404/1604/1804, centos7.5, and the crash messages are almost the same. The crash message on centos7.5 shows below: start fd 61 start fd 62 start fd 63 BUG: unable to handle kernel NULL pointer dereference at (null) IP: __wake_up_common+0x2e/0x90 PGD 0 Oops: 0000 [#1] SMP Modules linked in: test(OE) xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter devlink sunrpc kvm_intel kvm irqbypass crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd sg ppdev pcspkr virtio_balloon parport_pc parport i2c_piix4 joydev ip_tables xfs libcrc32c sr_mod cdrom sd_mod crc_t10dif crct10dif_generic ata_generic pata_acpi virtio_scsi virtio_console virtio_net cirrus drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm crct10dif_pclmul crct10dif_common crc32c_intel drm ata_piix serio_raw libata virtio_pci virtio_ring i2c_core virtio floppy dm_mirror dm_region_hash dm_log dm_mod CPU: 2 PID: 1820 Comm: test_fd Kdump: loaded Tainted: G OE ------------ 3.10.0-862.3.3.el7.x86_64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 task: ffff8e92b9431fa0 ti: ffff8e94247a0000 task.ti: ffff8e94247a0000 RIP: 0010:__wake_up_common+0x2e/0x90 RSP: 0018:ffff8e94247a2d18 EFLAGS: 00010086 RAX: 0000000000000000 RBX: ffffffff9d09daa0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffffff9d09daa0 RBP: ffff8e94247a2d50 R08: 0000000000000000 R09: ffff8e92b95dfda8 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff9d09daa8 R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000003 FS: 0000000000000000(0000) GS:ffff8e9434e80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000017c686000 CR4: 00000000000207e0 Call Trace: __wake_up+0x39/0x50 expand_files+0x131/0x250 __alloc_fd+0x47/0x170 get_unused_fd_flags+0x30/0x40 test_fd+0x12a/0x1c0 [test] kthread+0xd1/0xe0 ret_from_fork_nospec_begin+0x21/0x21 Code: 66 90 55 48 89 e5 41 57 41 89 f7 41 56 41 89 ce 41 55 41 54 49 89 fc 49 83 c4 08 53 48 83 ec 10 48 8b 47 08 89 55 cc 4c 89 45 d0 <48> 8b 08 49 39 c4 48 8d 78 e8 4c 8d 69 e8 75 08 eb 3b 4c 89 ef RIP __wake_up_common+0x2e/0x90 RSP <ffff8e94247a2d18> CR2: 0000000000000000 This issue exists since CentOS 7.5 3.10.0-862 and CentOS 7.4 (3.10.0-693.21.1 ) is ok. Root cause: the item 'resize_wait' is not initialized before being used. Reported-by: Richard Zhang <zhang.zijian@h3c.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
* fs: add ksys_close() wrapper; remove in-kernel calls to sys_close()Dominik Brodowski2018-04-021-0/+1
| | | | | | | | | | | | | | | | | | | | Using the ksys_close() wrapper allows us to get rid of in-kernel calls to the sys_close() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_close(), with one subtle difference: The few places which checked the return value did not care about the return value re-writing in sys_close(), so simply use a wrapper around __close_fd(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
* fs: add ksys_dup{,3}() helper; remove in-kernel calls to sys_dup{,3}()Dominik Brodowski2018-04-021-3/+13
| | | | | | | | | | | | | | | | | | | Using ksys_dup() and ksys_dup3() as helper functions allows us to avoid the in-kernel calls to the sys_dup() and sys_dup3() syscalls. The ksys_ prefix denotes that these functions are meant as a drop-in replacement for the syscalls. In particular, they use the same calling convention as sys_dup{,3}(). In the near future, the fs-external callers of ksys_dup{,3}() should be converted to call do_dup2() directly. Then, ksys_dup{,3}() can be moved within sys_dup{,3}() again. This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
* Merge branch 'work.misc' of ↵Linus Torvalds2018-01-311-5/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs updates from Al Viro: "All kinds of misc stuff, without any unifying topic, from various people. Neil's d_anon patch, several bugfixes, introduction of kvmalloc analogue of kmemdup_user(), extending bitfield.h to deal with fixed-endians, assorted cleanups all over the place..." * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits) alpha: osf_sys.c: use timespec64 where appropriate alpha: osf_sys.c: fix put_tv32 regression jffs2: Fix use-after-free bug in jffs2_iget()'s error handling path dcache: delete unused d_hash_mask dcache: subtract d_hash_shift from 32 in advance fs/buffer.c: fold init_buffer() into init_page_buffers() fs: fold __inode_permission() into inode_permission() fs: add RWF_APPEND sctp: use vmemdup_user() rather than badly open-coding memdup_user() snd_ctl_elem_init_enum_names(): switch to vmemdup_user() replace_user_tlv(): switch to vmemdup_user() new primitive: vmemdup_user() memdup_user(): switch to GFP_USER eventfd: fold eventfd_ctx_get() into eventfd_ctx_fileget() eventfd: fold eventfd_ctx_read() into eventfd_read() eventfd: convert to use anon_inode_getfd() nfs4file: get rid of pointless include of btrfs.h uvc_v4l2: clean copyin/copyout up vme_user: don't use __copy_..._user() usx2y: don't bother with memdup_user() for 16-byte structure ...
| * fs/file.c: trim includesAl Viro2017-12-051-5/+0
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | fs: Eliminate cond_resched_rcu_qs() in favor of cond_resched()Paul E. McKenney2017-12-041-1/+1
|/ | | | | | | | | | Now that cond_resched() also provides RCU quiescent states when needed, it can be used in place of cond_resched_rcu_qs(). This commit therefore makes this change. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: <linux-fsdevel@vger.kernel.org>
* Merge branch 'work.misc' of ↵Linus Torvalds2017-11-171-5/+7
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs updates from Al Viro: "Assorted stuff, really no common topic here" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vfs: grab the lock instead of blocking in __fd_install during resizing vfs: stop clearing close on exec when closing a fd include/linux/fs.h: fix comment about struct address_space fs: make fiemap work from compat_ioctl coda: fix 'kernel memory exposure attempt' in fsync pstore: remove unneeded unlikely() vfs: remove unneeded unlikely() stubs for mount_bdev() and kill_block_super() in !CONFIG_BLOCK case make vfs_ustat() static do_handle_open() should be static elf_fdpic: fix unused variable warning fold destroy_super() into __put_super() new helper: destroy_unused_super() fix address space warnings in ipc/ acct.h: get rid of detritus
| * vfs: grab the lock instead of blocking in __fd_install during resizingMateusz Guzik2017-11-051-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | Explicit locking in the fallback case provides a safe state of the table. Getting rid of blocking semantics makes __fd_install usable again in non-sleepable contexts, which easies backporting efforts. There is a side effect of slightly nicer assembly for the common case as might_sleep can now be removed. Signed-off-by: Mateusz Guzik <mguzik@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * vfs: stop clearing close on exec when closing a fdMateusz Guzik2017-11-051-1/+0
| | | | | | | | | | | | | | | | Codepaths allocating a fd always make sure the bit is set/unset depending on flags, thus clearing on close is redundant. Signed-off-by: Mateusz Guzik <mguzik@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fs/file.c: replace alloc_fdmem() with kvmalloc() alternativeMichal Hocko2017-07-061-18/+4
| | | | | | | | | | | There is no real reason to duplicate kvmalloc* helpers so drop alloc_fdmem and replace it with the appropriate library function. Link: http://lkml.kernel.org/r/20170531155145.17111-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmalloc: use __GFP_HIGHMEM implicitlyMichal Hocko2017-05-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | __vmalloc* allows users to provide gfp flags for the underlying allocation. This API is quite popular $ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l 77 The only problem is that many people are not aware that they really want to give __GFP_HIGHMEM along with other flags because there is really no reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages which are mapped to the kernel vmalloc space. About half of users don't use this flag, though. This signals that we make the API unnecessarily too complex. This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM are simplified and drop the flag. Link: http://lkml.kernel.org/r/20170307141020.29107-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Cristopher Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-1/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* fs/file: more unsigned file descriptorsAlexey Dobriyan2016-09-271-17/+17
| | | | | | | | | | | | | | | | | | | | | | | Propagate unsignedness for grand total of 149 bytes: $ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux add/remove: 0/0 grow/shrink: 0/10 up/down: 0/-149 (-149) function old new delta set_close_on_exec 99 98 -1 put_files_struct 201 200 -1 get_close_on_exec 59 58 -1 do_prlimit 498 497 -1 do_execveat_common.isra 1662 1661 -1 __close_fd 178 173 -5 do_dup2 219 204 -15 seq_show 685 660 -25 __alloc_fd 384 357 -27 dup_fd 718 646 -72 It mostly comes from converting "unsigned int" to "long" for bit operations. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* give readdir(2)/getdents(2)/etc. uniform exclusion with lseek()Al Viro2016-05-021-0/+5
| | | | | | same as read() on regular files has, and for the same reason. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* kmemcg: account certain kmem allocations to memcgVladimir Davydov2016-01-141-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mark those kmem allocations that are known to be easily triggered from userspace as __GFP_ACCOUNT/SLAB_ACCOUNT, which makes them accounted to memcg. For the list, see below: - threadinfo - task_struct - task_delay_info - pid - cred - mm_struct - vm_area_struct and vm_region (nommu) - anon_vma and anon_vma_chain - signal_struct - sighand_struct - fs_struct - files_struct - fdtable and fdtable->full_fds_bits - dentry and external_name - inode for all filesystems. This is the most tedious part, because most filesystems overwrite the alloc_inode method. The list is far from complete, so feel free to add more objects. Nevertheless, it should be close to "account everything" approach and keep most workloads within bounds. Malevolent users will be able to breach the limit, but this was possible even with the former "account everything" approach (simply because it did not account everything in fact). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> 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>
* fs/file.c: __const_max is actually __const_min :-)Rasmus Villemoes2015-12-061-3/+3
| | | | | | | | | 7f4b36f9bb930 "get rid of files_defer_init()" inexplicably changed a min() to a __const_max() - but the __const_max macro actually gives the minimum... So no functional change, just less confusing naming. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: clear remainder of 'full_fds_bits' in dup_fd()Eric Biggers2015-11-051-32/+32
| | | | | | | | | This fixes a bug from commit f3f86e33dc3d ("vfs: Fix pathological performance case for __alloc_fd()"). v2: refactor to share fd bitmap copying code Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vfs: conditionally clear close-on-exec flagLinus Torvalds2015-10-311-1/+2
| | | | | | | | | | | | | | | We clear the close-on-exec flag when opening and closing files, and the bit was almost always already clear before. Avoid dirtying the cacheline if the clearning isn't necessary. That avoids unnecessary cacheline dirtying and bouncing in multi-socket environments. Eric Dumazet has a file descriptor benchmark that goes 4% faster from this on his two-socket machine. It's probably partly superlinear improvement due to getting slightly less spinlock contention on the file_lock spinlock due to less work in the critical section. Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vfs: Fix pathological performance case for __alloc_fd()Linus Torvalds2015-10-311-4/+35
| | | | | | | | | | | | | | | | | | | | | | | | | Al Viro points out that: > > * [Linux-specific aside] our __alloc_fd() can degrade quite badly > > with some use patterns. The cacheline pingpong in the bitmap is probably > > inevitable, unless we accept considerably heavier memory footprint, > > but we also have a case when alloc_fd() takes O(n) and it's _not_ hard > > to trigger - close(3);open(...); will have the next open() after that > > scanning the entire in-use bitmap. And Eric Dumazet has a somewhat realistic multithreaded microbenchmark that opens and closes a lot of sockets with minimal work per socket. This patch largely fixes it. We keep a 2nd-level bitmap of the open file bitmaps, showing which words are already full. So then we can traverse that second-level bitmap to efficiently skip already allocated file descriptors. On his benchmark, this improves performance by up to an order of magnitude, by avoiding the excessive open file bitmap scanning. Tested-and-acked-by: Eric Dumazet <edumazet@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/file.c: __fget() and dup2() atomicity rulesEric Dumazet2015-07-011-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __fget() does lockless fetch of pointer from the descriptor table, attempts to grab a reference and treats "it was already zero" as "it's already gone from the table, we just hadn't seen the store, let's fail". Unfortunately, that breaks the atomicity of dup2() - __fget() might see the old pointer, notice that it's been already dropped and treat that as "it's closed". What we should be getting is either the old file or new one, depending whether we come before or after dup2(). Dmitry had following test failing sometimes : int fd; void *Thread(void *x) { char buf; int n = read(fd, &buf, 1); if (n != 1) exit(printf("read failed: n=%d errno=%d\n", n, errno)); return 0; } int main() { fd = open("/dev/urandom", O_RDONLY); int fd2 = open("/dev/urandom", O_RDONLY); if (fd == -1 || fd2 == -1) exit(printf("open failed\n")); pthread_t th; pthread_create(&th, 0, Thread, 0); if (dup2(fd2, fd) == -1) exit(printf("dup2 failed\n")); pthread_join(th, 0); if (close(fd) == -1) exit(printf("close failed\n")); if (close(fd2) == -1) exit(printf("close failed\n")); printf("DONE\n"); return 0; } Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/file.c: don't acquire files->file_lock in fd_install()Eric Dumazet2015-07-011-19/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mateusz Guzik reported : Currently obtaining a new file descriptor results in locking fdtable twice - once in order to reserve a slot and second time to fill it. Holding the spinlock in __fd_install() is needed in case a resize is done, or to prevent a resize. Mateusz provided an RFC patch and a micro benchmark : http://people.redhat.com/~mguzik/pipebench.c A resize is an unlikely operation in a process lifetime, as table size is at least doubled at every resize. We can use RCU instead of the spinlock. __fd_install() must wait if a resize is in progress. The resize must block new __fd_install() callers from starting, and wait that ongoing install are finished (synchronize_sched()) resize should be attempted by a single thread to not waste resources. rcu_sched variant is used, as __fd_install() and expand_fdtable() run from process context. It gives us a ~30% speedup using pipebench on a dual Intel(R) Xeon(R) CPU E5-2696 v2 @ 2.50GHz Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Mateusz Guzik <mguzik@redhat.com> Acked-by: Mateusz Guzik <mguzik@redhat.com> Tested-by: Mateusz Guzik <mguzik@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* mm: rcu-protected get_mm_exe_file()Konstantin Khlebnikov2015-04-171-2/+1
| | | | | | | | | | | | | | | This patch removes mm->mmap_sem from mm->exe_file read side. Also it kills dup_mm_exe_file() and moves exe_file duplication into dup_mmap() where both mmap_sems are locked. [akpm@linux-foundation.org: fix comment typo] Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> 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>
* Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-10-131-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - changes related to No-CBs CPUs and NO_HZ_FULL - RCU-tasks implementation - torture-test updates - miscellaneous fixes - locktorture updates - RCU documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) workqueue: Use cond_resched_rcu_qs macro workqueue: Add quiescent state between work items locktorture: Cleanup header usage locktorture: Cannot hold read and write lock locktorture: Fix __acquire annotation for spinlock irq locktorture: Support rwlocks rcu: Eliminate deadlock between CPU hotplug and expedited grace periods locktorture: Document boot/module parameters rcutorture: Rename rcutorture_runnable parameter locktorture: Add test scenario for rwsem_lock locktorture: Add test scenario for mutex_lock locktorture: Make torture scripting account for new _runnable name locktorture: Introduce torture context locktorture: Support rwsems locktorture: Add infrastructure for torturing read locks torture: Address race in module cleanup locktorture: Make statistics generic locktorture: Teach about lock debugging locktorture: Support mutexes locktorture: Add documentation ...
| * rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loopsPaul E. McKenney2014-09-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU-tasks requires the occasional voluntary context switch from CPU-bound in-kernel tasks. In some cases, this requires instrumenting cond_resched(). However, there is some reluctance to countenance unconditionally instrumenting cond_resched() (see http://lwn.net/Articles/603252/), so this commit creates a separate cond_resched_rcu_qs() that may be used in place of cond_resched() in locations prone to long-duration in-kernel looping. This commit currently instruments only RCU-tasks. Future possibilities include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce IPI usage. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* | missing annotation in fs/file.cAl Viro2014-10-091-0/+1
|/ | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/file.c: don't open-code kvfree()Al Viro2014-05-061-8/+3
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-linus' of ↵Linus Torvalds2014-04-121-7/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "The first vfs pile, with deep apologies for being very late in this window. Assorted cleanups and fixes, plus a large preparatory part of iov_iter work. There's a lot more of that, but it'll probably go into the next merge window - it *does* shape up nicely, removes a lot of boilerplate, gets rid of locking inconsistencie between aio_write and splice_write and I hope to get Kent's direct-io rewrite merged into the same queue, but some of the stuff after this point is having (mostly trivial) conflicts with the things already merged into mainline and with some I want more testing. This one passes LTP and xfstests without regressions, in addition to usual beating. BTW, readahead02 in ltp syscalls testsuite has started giving failures since "mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages" - might be a false positive, might be a real regression..." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) missing bits of "splice: fix racy pipe->buffers uses" cifs: fix the race in cifs_writev() ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure kill generic_file_buffered_write() ocfs2_file_aio_write(): switch to generic_perform_write() ceph_aio_write(): switch to generic_perform_write() xfs_file_buffered_aio_write(): switch to generic_perform_write() export generic_perform_write(), start getting rid of generic_file_buffer_write() generic_file_direct_write(): get rid of ppos argument btrfs_file_aio_write(): get rid of ppos kill the 5th argument of generic_file_buffered_write() kill the 4th argument of __generic_file_aio_write() lustre: don't open-code kernel_recvmsg() ocfs2: don't open-code kernel_recvmsg() drbd: don't open-code kernel_recvmsg() constify blk_rq_map_user_iov() and friends lustre: switch to kernel_sendmsg() ocfs2: don't open-code kernel_sendmsg() take iov_iter stuff to mm/iov_iter.c process_vm_access: tidy up a bit ...
| * get rid of files_defer_init()Al Viro2014-04-011-7/+4
| | | | | | | | | | | | | | | | the only thing it's doing these days is calculation of upper limit for fs.nr_open sysctl and that can be done statically Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-03-311-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "Main changes: - Torture-test changes, including refactoring of rcutorture and introduction of a vestigial locktorture. - Real-time latency fixes. - Documentation updates. - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) rcu: Provide grace-period piggybacking API rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c notifier: Substitute rcu_access_pointer() for rcu_dereference_raw() Documentation/memory-barriers.txt: Clarify release/acquire ordering rcutorture: Save kvm.sh output to log rcutorture: Add a lock_busted to test the test rcutorture: Place kvm-test-1-run.sh output into res directory rcutorture: Rename TREE_RCU-Kconfig.txt locktorture: Add kvm-recheck.sh plug-in for locktorture rcutorture: Gracefully handle NULL cleanup hooks locktorture: Add vestigial locktorture configuration rcutorture: Introduce "rcu" directory level underneath configs rcutorture: Rename kvm-test-1-rcu.sh rcutorture: Remove RCU dependencies from ver_functions.sh API rcutorture: Create CFcommon file for common Kconfig parameters rcutorture: Create config files for scripted test-the-test testing rcutorture: Add an rcu_busted to test the test locktorture: Add a lock-torture kernel module rcutorture: Abstract kvm-recheck.sh ...
| * fs: Substitute rcu_access_pointer() for rcu_dereference_raw()Paul E. McKenney2014-02-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (Trivial patch.) If the code is looking at the RCU-protected pointer itself, but not dereferencing it, the rcu_dereference() functions can be downgraded to rcu_access_pointer(). This commit makes this downgrade in __alloc_fd(), which simply compares the RCU-protected pointer against NULL with no dereferencing. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* | vfs: Don't let __fdget_pos() get FMODE_PATH filesEric Biggers2014-03-231-15/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit bd2a31d522344 ("get rid of fget_light()") introduced the __fdget_pos() function, which returns the resulting file pointer and fdput flags combined in an 'unsigned long'. However, it also changed the behavior to return files with FMODE_PATH set, which shouldn't happen because read(), write(), lseek(), etc. aren't allowed on such files. This commit restores the old behavior. This regression actually had no effect on read() and write() since FMODE_READ and FMODE_WRITE are not set on file descriptors opened with O_PATH, but it did cause lseek() on a file descriptor opened with O_PATH to fail with ESPIPE rather than EBADF. Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | get rid of fget_light()Al Viro2014-03-101-13/+43
|/ | | | | | | | instead of returning the flags by reference, we can just have the low-level primitive return those in lower bits of unsigned long, with struct file * derived from the rest. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/file.c:fdtable: avoid triggering OOMs from alloc_fdmemEric W. Biederman2014-02-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recently due to a spike in connections per second memcached on 3 separate boxes triggered the OOM killer from accept. At the time the OOM killer was triggered there was 4GB out of 36GB free in zone 1. The problem was that alloc_fdtable was allocating an order 3 page (32KiB) to hold a bitmap, and there was sufficient fragmentation that the largest page available was 8KiB. I find the logic that PAGE_ALLOC_COSTLY_ORDER can't fail pretty dubious but I do agree that order 3 allocations are very likely to succeed. There are always pathologies where order > 0 allocations can fail when there are copious amounts of free memory available. Using the pigeon hole principle it is easy to show that it requires 1 page more than 50% of the pages being free to guarantee an order 1 (8KiB) allocation will succeed, 1 page more than 75% of the pages being free to guarantee an order 2 (16KiB) allocation will succeed and 1 page more than 87.5% of the pages being free to guarantee an order 3 allocate will succeed. A server churning memory with a lot of small requests and replies like memcached is a common case that if anything can will skew the odds against large pages being available. Therefore let's not give external applications a practical way to kill linux server applications, and specify __GFP_NORETRY to the kmalloc in alloc_fdmem. Unless I am misreading the code and by the time the code reaches should_alloc_retry in __alloc_pages_slowpath (where __GFP_NORETRY becomes signification). We have already tried everything reasonable to allocate a page and the only thing left to do is wait. So not waiting and falling back to vmalloc immediately seems like the reasonable thing to do even if there wasn't a chance of triggering the OOM killer. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Cong Wang <cwang@twopensource.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: __fget_light() can use __fget() in slow pathOleg Nesterov2014-01-251-11/+3
| | | | | | | | The slow path in __fget_light() can use __fget() to avoid the code duplication. Saves 232 bytes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: factor out common code in fget_light() and fget_raw_light()Oleg Nesterov2014-01-251-24/+9
| | | | | | | | | Apart from FMODE_PATH check fget_light() and fget_raw_light() are identical, shift the code into the new helper, __fget_light(fd, mask). Saves 208 bytes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: factor out common code in fget() and fget_raw()Oleg Nesterov2014-01-251-17/+8
| | | | | | | | | Apart from FMODE_PATH check fget() and fget_raw() are identical, shift the code into the new simple helper, __fget(fd, mask). Saves 160 bytes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* change close_files() to use rcu_dereference_raw(files->fdt)Oleg Nesterov2014-01-251-17/+9
| | | | | | | | | | | | | | | | | | | | | put_files_struct() and close_files() do rcu_read_lock() to make rcu_dereference_check_fdtable() happy. This looks a bit ugly, files_fdtable() just reads the pointer, we can simply use rcu_dereference_raw() to avoid the warning. The patch also changes close_files() to return fdt, this avoids another rcu_read_lock()/files_fdtable() in put_files_struct(). I think close_files() needs more cleanups: - we do not need xchg() exactly because we are the last user of this files_struct - "if (file)" should be turned into WARN_ON(!file) Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* introduce __fcheck_files() to fix rcu_dereference_check_fdtable(), kill ↵Oleg Nesterov2014-01-251-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rcu_my_thread_group_empty() rcu_dereference_check_fdtable() looks very wrong, 1. rcu_my_thread_group_empty() was added by 844b9a8707f1 "vfs: fix RCU-lockdep false positive due to /proc" but it doesn't really fix the problem. A CLONE_THREAD (without CLONE_FILES) task can hit the same race with get_files_struct(). And otoh rcu_my_thread_group_empty() can suppress the correct warning if the caller is the CLONE_FILES (without CLONE_THREAD) task. 2. files->count == 1 check is not really right too. Even if this files_struct is not shared it is not safe to access it lockless unless the caller is the owner. Otoh, this check is sub-optimal. files->count == 0 always means it is safe to use it lockless even if files != current->files, but put_files_struct() has to take rcu_read_lock(). See the next patch. This patch removes the buggy checks and turns fcheck_files() into __fcheck_files() which uses rcu_dereference_raw(), the "unshared" callers, fget_light() and fget_raw_light(), can use it to avoid the warning from RCU-lockdep. fcheck_files() is trivially reimplemented as rcu_lockdep_assert() plus __fcheck_files(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* don't bother with deferred freeing of fdtablesAl Viro2013-05-011-66/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* locking: Various static lock initializer fixesThomas Gleixner2013-02-191-1/+1
| | | | | | | | | The static lock initializers want to be fed the proper name of the lock and not some random string. In mainline random strings are obfuscating the readability of debug output, but for RT they prevent the spinlock substitution. Fix it up. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* misc: remove __dev* attributes.Greg Kroah-Hartman2013-01-031-1/+1
| | | | | | | | | | | | | | CONFIG_HOTPLUG is going away as an option. As a result, the __dev* markings need to be removed. This change removes the last of the __dev* markings from the kernel from a variety of different, tiny, places. Based on patches originally written by Bill Pemberton, but redone by me in order to handle some of the coding style issues better, by hand. Cc: Bill Pemberton <wfp5p@virginia.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-12-121-6/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull big execve/kernel_thread/fork unification series from Al Viro: "All architectures are converted to new model. Quite a bit of that stuff is actually shared with architecture trees; in such cases it's literally shared branch pulled by both, not a cherry-pick. A lot of ugliness and black magic is gone (-3KLoC total in this one): - kernel_thread()/kernel_execve()/sys_execve() redesign. We don't do syscalls from kernel anymore for either kernel_thread() or kernel_execve(): kernel_thread() is essentially clone(2) with callback run before we return to userland, the callbacks either never return or do successful do_execve() before returning. kernel_execve() is a wrapper for do_execve() - it doesn't need to do transition to user mode anymore. As a result kernel_thread() and kernel_execve() are arch-independent now - they live in kernel/fork.c and fs/exec.c resp. sys_execve() is also in fs/exec.c and it's completely architecture-independent. - daemonize() is gone, along with its parts in fs/*.c - struct pt_regs * is no longer passed to do_fork/copy_process/ copy_thread/do_execve/search_binary_handler/->load_binary/do_coredump. - sys_fork()/sys_vfork()/sys_clone() unified; some architectures still need wrappers (ones with callee-saved registers not saved in pt_regs on syscall entry), but the main part of those suckers is in kernel/fork.c now." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (113 commits) do_coredump(): get rid of pt_regs argument print_fatal_signal(): get rid of pt_regs argument ptrace_signal(): get rid of unused arguments get rid of ptrace_signal_deliver() arguments new helper: signal_pt_regs() unify default ptrace_signal_deliver flagday: kill pt_regs argument of do_fork() death to idle_regs() don't pass regs to copy_process() flagday: don't pass regs to copy_thread() bfin: switch to generic vfork, get rid of pointless wrappers xtensa: switch to generic clone() openrisc: switch to use of generic fork and clone unicore32: switch to generic clone(2) score: switch to generic fork/vfork/clone c6x: sanitize copy_thread(), get rid of clone(2) wrapper, switch to generic clone() take sys_fork/sys_vfork/sys_clone prototypes to linux/syscalls.h mn10300: switch to generic fork/vfork/clone h8300: switch to generic fork/vfork/clone tile: switch to generic clone() ... Conflicts: arch/microblaze/include/asm/Kbuild
| * kill daemonize()Al Viro2012-11-281-6/+0
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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