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* get_maintainer: look for arbitrary letter prefixes in sectionsJoe Perches2016-12-131-3/+9
| | | | | | | | | | | | | | | | | Jani Nikula proposes patches to add a few new letter prefixes for "B:" bug reporting and "C:" maintainer chatting to the various sections of MAINTAINERS. Add a generic mechanism to get_maintainer.pl to find sections that have any combination of "[A-Z]" letter prefix types in a section. Link: http://lkml.kernel.org/r/1477332323.1984.8.camel@perches.com Signed-off-by: Joe Perches <joe@perches.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Dave Airlie <airlied@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: add Kconfig option to set default console loglevelOlof Johansson2016-12-132-1/+25
| | | | | | | | | | | | | | | | | | | Add a configuration option to set the default console loglevel. This is, as before, still possible to override at runtime through bootargs (loglevel=<x>), sysrq and /proc/printk. There are cases where adding additional arguments on the commandline is impractical, and changing the default for the kernel when being built makes more sense. Provide such a method here, for those who choose to do so. Also, while touching this code, clarify the difference between MESSAGE_LOGLEVEL_DEFAULT and CONSOLE_LOGLEVEL_DEFAULT. Link: http://lkml.kernel.org/r/1479676829-30031-1-git-send-email-olof@lixom.net Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/sound: handle more message headersPetr Mladek2016-12-131-6/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines") allows to define more message headers for a single message. The motivation is that continuous lines might get mixed. Therefore it make sense to define the right log level for every piece of a cont line. This patch allows to copy only the real message level. We should ignore KERN_CONT because <filename:line> is added for each message. By other words, we want to know where each piece of the line comes from. [pmladek@suse.com: fix a check of the valid message level] Link: http://lkml.kernel.org/r/20161111183444.GE2145@dhcp128.suse.cz Link: http://lkml.kernel.org/r/1478695291-12169-5-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Joe Perches <joe@perches.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: David Sterba <dsterba@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/btrfs: handle more message headersPetr Mladek2016-12-132-11/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines") allows to define more message headers for a single message. The motivation is that continuous lines might get mixed. Therefore it make sense to define the right log level for every piece of a cont line. The current btrfs_printk() macros do not support continuous lines at the moment. But better be prepared for a custom messages and avoid potential "lvl" buffer overflow. This patch iterates over the entire message header. It is interested only into the message level like the original code. This patch also introduces PRINTK_MAX_SINGLE_HEADER_LEN. Three bytes are enough for the message level header at the moment. But it used to be three, see the commit 04d2c8c83d0e ("printk: convert the format for KERN_<LEVEL> to a 2 byte pattern"). Also I fixed the default ratelimit level. It looked very strange when it was different from the default log level. [pmladek@suse.com: Fix a check of the valid message level] Link: http://lkml.kernel.org/r/20161111183236.GD2145@dhcp128.suse.cz Link: http://lkml.kernel.org/r/1478695291-12169-4-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: David Sterba <dsterba@suse.com> Cc: Joe Perches <joe@perches.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/kdb: handle more message headersPetr Mladek2016-12-132-1/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines") allows to define more message headers for a single message. The motivation is that continuous lines might get mixed. Therefore it make sense to define the right log level for every piece of a cont line. This patch introduces printk_skip_headers() that will skip all headers and uses it in the kdb code instead of printk_skip_level(). This approach helps to fix other printk_skip_level() users independently. Link: http://lkml.kernel.org/r/1478695291-12169-3-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Joe Perches <joe@perches.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: David Sterba <dsterba@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/NMI: handle continuous lines and missing newlinePetr Mladek2016-12-131-28/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines") added back KERN_CONT message header. As a result it might appear in the middle of the line when the parts are squashed via the temporary NMI buffer. A reasonable solution seems to be to split the text in the NNI temporary not only by newlines but also by the message headers. Another solution would be to filter out KERN_CONT when writing to the temporary buffer. But this would complicate the lockless handling. Also it would not solve problems with a missing newline that was there even before the KERN_CONT stuff. This patch moves the temporary buffer handling into separate function. I played with it and it seems that using the char pointers make the code easier to read. Also it prints the final newline as a continuous line. Finally, it moves handling of the s->len overflow into the paranoid check. And allows to recover from the disaster. Link: http://lkml.kernel.org/r/1478695291-12169-2-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Joe Perches <joe@perches.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: David Sterba <dsterba@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/NMI: fix up handling of the full nmi log bufferPetr Mladek2016-12-131-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | vsnprintf() adds the trailing '\0' but it does not count it into the number of printed characters. The result is that there is one byte less space for the real characters in the buffer. The broken check for the free space might cause that we will repeatedly try to print 1 character into the buffer, never reach the full buffer, and do not count the messages as missed. Also vsnprintf() returns the number of characters that would be printed if the buffer was big enough. As a result, s->len might be bigger than the size of the buffer[*]. And the printk() function might return bigger len than it really printed. Both problems are fixed by using vscnprintf() instead. Note that I though about increasing the number of missed messages even when the message was shrunken. But it made the code even more complicated. I think that it is not worth it. Shrunken messages are usually easy to recognize. And it should be a corner case. [*] The overflown s->len value is crazy and unexpected. I "made a mistake" and reported this situation as an internal error when fixed handling of PR_CONT headers in some other patch. Link: http://lkml.kernel.org/r/20161208174912.GA17042@linux.suse Signed-off-by: Petr Mladek <pmladek@suse.com> CcL Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Chris Mason <clm@fb.com> Cc: David Sterba <dsterba@suse.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Josef Bacik <jbacik@fb.com> Cc: Joe Perches <joe@perches.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Takashi Iwai <tiwai@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* compiler-gcc.h: use "proved" instead of "proofed"Benjamin Peterson2016-12-131-1/+1
| | | | | | | Link: http://lkml.kernel.org/r/1477894241.1103202.772260161.1B0A5995@webmail.messagingengine.com Signed-off-by: Benjamin Peterson <bp@benjamin.pe> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hung_task: decrement sysctl_hung_task_warnings only if it is positiveTetsuo Handa2016-12-131-1/+2
| | | | | | | | | | | | | | Since sysctl_hung_task_warnings == -1 is allowed (infinite warnings), commit 48a6d64edadb ("hung_task: allow hung_task_panic when hung_task_warnings is 0") should decrement it only when it is not -1. This prevents the kernel from ceasing warnings after the first 4294967295 ;) Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: John Siddle <jsiddle@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/proc: calculate /proc/* and /proc/*/task/* nlink at init timeAlexey Dobriyan2016-12-133-6/+15
| | | | | | | | | | | | | Runtime nlink calculation works but meh. I don't know how to do it at compile time, but I know how to do it at init time. Shift "2+" part into init time as a bonus. Link: http://lkml.kernel.org/r/20161122195549.GB29812@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/proc/base.c: save decrement during lookup/readdir in /proc/$PIDAlexey Dobriyan2016-12-131-4/+4
| | | | | | | | | | Comparison for "<" works equally well as comparison for "<=" but one SUB/LEA is saved (no, it is not optimised away, at least here). Link: http://lkml.kernel.org/r/20161122195143.GA29812@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/proc/array.c: slightly improve render_sigset_tRasmus Villemoes2016-12-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | format_decode and vsnprintf occasionally show up in perf top, so I went looking for places that might not need the full printf power. With the help of kprobes, I gathered some statistics on which format strings we mostly pass to vsnprintf. On a trivial desktop workload, I hit "%x" 25% of the time, so something apparently reads /proc/pid/status (which does 5*16 printf("%x") calls) a lot. With this patch, reading /proc/pid/status is 30% faster according to this microbenchmark: char buf[4096]; int i, fd; for (i = 0; i < 10000; ++i) { fd = open("/proc/self/status", O_RDONLY); read(fd, buf, sizeof(buf)); close(fd); } Link: http://lkml.kernel.org/r/1474410485-1305-1-git-send-email-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andrei Vagin <avagin@openvz.org> Acked-by: Kees Cook <keescook@chromium.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: tweak comments about 2 stage open and everythingAlexey Dobriyan2016-12-131-8/+21
| | | | | | | | | | | | | | Some comments were obsoleted since commit 05c0ae21c034 ("try a saner locking for pde_opener..."). Some new comments added. Some confusing comments replaced with equally confusing ones. Link: http://lkml.kernel.org/r/20161029160231.GD1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: kmalloc struct pde_openerAlexey Dobriyan2016-12-131-1/+3
| | | | | | | | | | | | kzalloc is too much, half of the fields will be reinitialized anyway. If proc file doesn't have ->release hook (some still do not), clearing is unnecessary because it will be freed immediately. Link: http://lkml.kernel.org/r/20161029155747.GC1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: fix type of struct pde_opener::closing fieldAlexey Dobriyan2016-12-132-2/+2
| | | | | | | | | struct pde_opener::closing is boolean. Link: http://lkml.kernel.org/r/20161029155439.GB1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: just list_del() struct pde_openerAlexey Dobriyan2016-12-131-1/+1
| | | | | | | | | | list_del_init() is too much, structure will be freed in three lines anyway. Link: http://lkml.kernel.org/r/20161029155313.GA1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: make struct struct map_files_info::len unsigned intAlexey Dobriyan2016-12-131-1/+1
| | | | | | | | | | | | Linux doesn't support 4GB+ filenames in /proc, so unsigned long is too much. MOV r64, r/m64 is larger than MOV r32, r/m32. Link: http://lkml.kernel.org/r/20161029161123.GG1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: make struct pid_entry::len unsignedAlexey Dobriyan2016-12-131-1/+1
| | | | | | | | | | "unsigned int" is better on x86_64 because it most of the time it autoexpands to 64-bit value while "int" requires MOVSX instruction. Link: http://lkml.kernel.org/r/20161029160810.GF1246@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* proc: report no_new_privs stateKees Cook2016-12-132-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Similar to being able to examine if a process has been correctly confined with seccomp, the state of no_new_privs is equally interesting, so this adds it to /proc/$pid/status. Link: http://lkml.kernel.org/r/20161103214041.GA58566@beast Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jann Horn <jann@thejh.net> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rodrigo Freire <rfreire@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Robert Ho <robert.hu@intel.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Richard W.M. Jones" <rjones@redhat.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>
* mm/percpu.c: fix panic triggered by BUG_ON() falselyzijun_hu2016-12-131-4/+12
| | | | | | | | | | | | | | | | | | | | | As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kasan: turn on -fsanitize-address-use-after-scopeAndrey Ryabinin2016-12-131-0/+2
| | | | | | | | | | | | | | | | | | | | In the upcoming gcc7 release, the -fsanitize=kernel-address option at first implied new -fsanitize-address-use-after-scope option. This would cause link errors on older kernels because they don't have two new functions required for use-after-scope support. Therefore, gcc7 changed default to -fno-sanitize-address-use-after-scope. Now the kernel has everything required for that feature since commit 828347f8f9a5 ("kasan: support use-after-scope detection"). So, to make it work, we just have to enable use-after-scope in CFLAGS. Link: http://lkml.kernel.org/r/1481207977-28654-1-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kasan: eliminate long stalls during quarantine reductionDmitry Vyukov2016-12-131-46/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently we dedicate 1/32 of RAM for quarantine and then reduce it by 1/4 of total quarantine size. This can be a significant amount of memory. For example, with 4GB of RAM total quarantine size is 128MB and it is reduced by 32MB at a time. With 128GB of RAM total quarantine size is 4GB and it is reduced by 1GB. This leads to several problems: - freeing 1GB can take tens of seconds, causes rcu stall warnings and just introduces unexpected long delays at random places - if kmalloc() is called under a mutex, other threads stall on that mutex while a thread reduces quarantine - threads wait on quarantine_lock while one thread grabs a large batch of objects to evict - we walk the uncached list of object to free twice which makes all of the above worse - when a thread frees objects, they are already not accounted against global_quarantine.bytes; as the result we can have quarantine_size bytes in quarantine + unbounded amount of memory in large batches in threads that are in process of freeing Reduce size of quarantine in smaller batches to reduce the delays. The only reason to reduce it in batches is amortization of overheads, the new batch size of 1MB should be well enough to amortize spinlock lock/unlock and few function calls. Plus organize quarantine as a FIFO array of batches. This allows to not walk the list in quarantine_reduce() under quarantine_lock, which in turn reduces contention and is just faster. This improves performance of heavy load (syzkaller fuzzing) by ~20% with 4 CPUs and 32GB of RAM. Also this eliminates frequent (every 5 sec) drops of CPU consumption from ~400% to ~100% (one thread reduces quarantine while others are waiting on a mutex). Some reference numbers: 1. Machine with 4 CPUs and 4GB of memory. Quarantine size 128MB. Currently we free 32MB at at time. With new code we free 1MB at a time (1024 batches, ~128 are used). 2. Machine with 32 CPUs and 128GB of memory. Quarantine size 4GB. Currently we free 1GB at at time. With new code we free 8MB at a time (1024 batches, ~512 are used). 3. Machine with 4096 CPUs and 1TB of memory. Quarantine size 32GB. Currently we free 8GB at at time. With new code we free 4MB at a time (16K batches, ~8K are used). Link: http://lkml.kernel.org/r/1478756952-18695-1-git-send-email-dvyukov@google.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kasan: support panic_on_warnDmitry Vyukov2016-12-131-0/+2
| | | | | | | | | | | | | | | | | | If user sets panic_on_warn, he wants kernel to panic if there is anything barely wrong with the kernel. KASAN-detected errors are definitely not less benign than an arbitrary kernel WARNING. Panic after KASAN errors if panic_on_warn is set. We use this for continuous fuzzing where we want kernel to stop and reboot on any error. Link: http://lkml.kernel.org/r/1476694764-31986-1-git-send-email-dvyukov@google.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make transparent hugepage size publicHugh Dickins2016-12-132-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Test programs want to know the size of a transparent hugepage. While it is commonly the same as the size of a hugetlbfs page (shown as Hugepagesize in /proc/meminfo), that is not always so: powerpc implements transparent hugepages in a different way from hugetlbfs pages, so it's coincidence when their sizes are the same; and x86 and others can support more than one hugetlbfs page size. Add /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to show the THP size in bytes - it's the same for Anonymous and Shmem hugepages. Call it hpage_pmd_size (after HPAGE_PMD_SIZE) rather than hpage_size, in case some transparent support for pud and pgd pages is added later. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052200290.13021@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: David Rientjes <rientjes@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add cond_resched() in gather_pte_stats()Hugh Dickins2016-12-131-0/+1
| | | | | | | | | | | | | | | | The other pagetable walks in task_mmu.c have a cond_resched() after walking their ptes: add a cond_resched() in gather_pte_stats() too, for reading /proc/<id>/numa_maps. Only pagemap_pmd_range() has a cond_resched() in its (unusually expensive) pmd_trans_huge case: more should probably be added, but leave them unchanged for now. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052157400.13021@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add three more cond_resched() in swapoffHugh Dickins2016-12-131-7/+6
| | | | | | | | | | | | | | | | | | | Add a cond_resched() in the unuse_pmd_range() loop (so as to call it even when pmd none or trans_huge, like zap_pmd_range() does); and in the unuse_mm() loop (since that might skip over many vmas). shmem_unuse() and radix_tree_locate_item() look good enough already. Those were the obvious places, but in fact the stalls came from find_next_to_unuse(), which sometimes scans through many unused entries. Apply scan_swap_map()'s LATENCY_LIMIT of 256 there too; and only go off to test frontswap_map when a used entry is found. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052155140.13021@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Eric Dumazet <edumazet@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, page_alloc: keep pcp count and list contents in sync if struct page is ↵Mel Gorman2016-12-131-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | corrupted Vlastimil Babka pointed out that commit 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") will allow the per-cpu list counter to be out of sync with the per-cpu list contents if a struct page is corrupted. The consequence is an infinite loop if the per-cpu lists get fully drained by free_pcppages_bulk because all the lists are empty but the count is positive. The infinite loop occurs here do { batch_free++; if (++migratetype == MIGRATE_PCPTYPES) migratetype = 0; list = &pcp->lists[migratetype]; } while (list_empty(list)); What the user sees is a bad page warning followed by a soft lockup with interrupts disabled in free_pcppages_bulk(). This patch keeps the accounting in sync. Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") Link: http://lkml.kernel.org/r/20161202112951.23346-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> [4.7+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, rmap: handle anon_vma_prepare() common case inlineVlastimil Babka2016-12-132-36/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | anon_vma_prepare() is mostly a large "if (unlikely(...))" block, as the expected common case is that an anon_vma already exists. We could turn the condition around and return 0, but it also makes sense to do it inline and avoid a call for the common case. Bloat-o-meter naturally shows that inlining the check has some code size costs: add/remove: 1/1 grow/shrink: 4/0 up/down: 475/-373 (102) function old new delta __anon_vma_prepare - 359 +359 handle_mm_fault 2744 2796 +52 hugetlb_cow 1146 1170 +24 hugetlb_fault 2123 2145 +22 wp_page_copy 1469 1487 +18 anon_vma_prepare 373 - -373 Checking the asm however confirms that the hot paths now avoid a call, which is moved away. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20161116074005.22768-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: 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, debug: print raw struct page data in __dump_page()Vlastimil Babka2016-12-131-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __dump_page() is used when a page metadata inconsistency is detected, either by standard runtime checks, or extra checks in CONFIG_DEBUG_VM builds. It prints some of the relevant metadata, but not the whole struct page, which is based on unions and interpretation is dependent on the context. This means that sometimes e.g. a VM_BUG_ON_PAGE() checks certain field, which is however not printed by __dump_page() and the resulting bug report may then lack clues that could help in determining the root cause. This patch solves the problem by simply printing the whole struct page word by word, so no part is missing, but the interpretation of the data is left to developers. This is similar to e.g. x86_64 raw stack dumps. Example output: page:ffffea00000475c0 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x100000000000400(reserved) raw: 0100000000000400 0000000000000000 0000000000000000 00000001ffffffff raw: ffffea00000475e0 ffffea00000475e0 0000000000000000 0000000000000000 page dumped because: VM_BUG_ON_PAGE(1) [aryabinin@virtuozzo.com: suggested print_hex_dump()] Link: http://lkml.kernel.org/r/2ff83214-70fe-741e-bf05-fe4a4073ec3e@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: THP page cache support for ppc64Aneesh Kumar K.V2016-12-136-17/+100
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add arch specific callback in the generic THP page cache code that will deposit and withdarw preallocated page table. Archs like ppc64 use this preallocated table to store the hash pte slot information. Testing: kernel build of the patch series on tmpfs mounted with option huge=always The related thp stat: thp_fault_alloc 72939 thp_fault_fallback 60547 thp_collapse_alloc 603 thp_collapse_alloc_failed 0 thp_file_alloc 253763 thp_file_mapped 4251 thp_split_page 51518 thp_split_page_failed 1 thp_deferred_split_page 73566 thp_split_pmd 665 thp_zero_page_alloc 3 thp_zero_page_alloc_failed 0 [akpm@linux-foundation.org: remove unneeded parentheses, per Kirill] Link: http://lkml.kernel.org/r/20161113150025.17942-2-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move vma_is_anonymous check within pmd_move_must_withdrawAneesh Kumar K.V2016-12-133-15/+18
| | | | | | | | | | | | | | | | | | | | | | | Independent of whether the vma is for anonymous memory, some arches like ppc64 would like to override pmd_move_must_withdraw(). One option is to encapsulate the vma_is_anonymous() check for general architectures inside pmd_move_must_withdraw() so that is always called and architectures that need unconditional overriding can override this function. ppc64 needs to override the function when the MMU is configured to use hash PTE's. [bsingharora@gmail.com: reworked changelog] Link: http://lkml.kernel.org/r/20161113150025.17942-1-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add preempt points into __purge_vmap_area_lazy()Joel Fernandes2016-12-131-5/+9
| | | | | | | | | | | | | | | | | | | | Use cond_resched_lock to avoid holding the vmap_area_lock for a potentially long time and thus creating bad latencies for various workloads. [hch: split from a larger patch by Joel, wrote the crappy changelog] Link: http://lkml.kernel.org/r/1479474236-4139-11-git-send-email-hch@lst.de Signed-off-by: Joel Fernandes <joelaf@google.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: turn vmap_purge_lock into a mutexChristoph Hellwig2016-12-131-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The purge_lock spinlock causes high latencies with non RT kernel. This has been reported multiple times on lkml [1] [2] and affects applications like audio. This patch replaces it with a mutex to allow preemption while holding the lock. Thanks to Joel Fernandes for the detailed report and analysis as well as an earlier attempt at fixing this issue. [1] http://lists.openwall.net/linux-kernel/2016/03/23/29 [2] https://lkml.org/lkml/2016/10/9/59 Link: http://lkml.kernel.org/r/1479474236-4139-10-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mark all calls into the vmalloc subsystem as potentially sleepingChristoph Hellwig2016-12-131-1/+6
| | | | | | | | | | | | | | | | | | We will take a sleeping lock in later in this series, so this adds the proper safeguards. Link: http://lkml.kernel.org/r/1479474236-4139-9-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* x86/ldt: use vfree_atomic() to free ldt entriesAndrey Ryabinin2016-12-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | vfree() is going to use sleeping lock. free_ldt_struct() may be called with disabled preemption, therefore we must use vfree_atomic() here. E.g. call trace: vfree() free_ldt_struct() destroy_context_ldt() __mmdrop() finish_task_switch() schedule_tail() ret_from_fork() Link: http://lkml.kernel.org/r/1479474236-4139-7-git-send-email-hch@lst.de Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Joel Fernandes <joelaf@google.com> Cc: Jisheng Zhang <jszhang@marvell.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/fork: use vfree_atomic() to free thread stackAndrey Ryabinin2016-12-131-1/+1
| | | | | | | | | | | | | | | | | | vfree() is going to use sleeping lock. Thread stack freed in atomic context, therefore we must use vfree_atomic() here. Link: http://lkml.kernel.org/r/1479474236-4139-6-git-send-email-hch@lst.de Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Joel Fernandes <joelaf@google.com> Cc: Jisheng Zhang <jszhang@marvell.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add vfree_atomic()Andrey Ryabinin2016-12-132-6/+37
| | | | | | | | | | | | | | | | | | | | | | | We are going to use sleeping lock for freeing vmap. However some vfree() users want to free memory from atomic (but not from interrupt) context. For this we add vfree_atomic() - deferred variation of vfree() which can be used in any atomic context (except NMIs). [akpm@linux-foundation.org: tweak comment grammar] [aryabinin@virtuozzo.com: use raw_cpu_ptr() instead of this_cpu_ptr()] Link: http://lkml.kernel.org/r/1481553981-3856-1-git-send-email-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/1479474236-4139-5-git-send-email-hch@lst.de Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Joel Fernandes <joelaf@google.com> Cc: Jisheng Zhang <jszhang@marvell.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: refactor __purge_vmap_area_lazy()Christoph Hellwig2016-12-131-45/+35
| | | | | | | | | | | | | | | | | | | | | | Move the purge_lock synchronization to the callers, move the call to purge_fragmented_blocks_allcpus at the beginning of the function to the callers that need it, move the force_flush behavior to the caller that needs it, and pass start and end by value instead of by reference. No change in behavior. Link: http://lkml.kernel.org/r/1479474236-4139-4-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove free_unmap_vmap_area_addr()Christoph Hellwig2016-12-131-13/+8
| | | | | | | | | | | | | | | | | Just inline it into the only caller. Link: http://lkml.kernel.org/r/1479474236-4139-3-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove free_unmap_vmap_area_noflush()Christoph Hellwig2016-12-131-11/+2
| | | | | | | | | | | | | | | | | | | | | | | | Patch series "reduce latency in __purge_vmap_area_lazy", v2. This patch (of 10): Sort out the long lock hold times in __purge_vmap_area_lazy. It is based on a patch from Joel. Inline free_unmap_vmap_area_noflush() it into the only caller. Link: http://lkml.kernel.org/r/1479474236-4139-2-git-send-email-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Jisheng Zhang <jszhang@marvell.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Dias <joaodias@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: workingset: update shadow limit to reflect bigger active listJohannes Weiner2016-12-131-19/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list") the size of the active file list is no longer limited to half of memory. Increase the shadow node limit accordingly to avoid throwing out shadow entries that might still result in eligible refaults. The exact size of the active list now depends on the overall size of the page cache, but converges toward taking up most of the space: In mm/vmscan.c::inactive_list_is_low(), * total target max * memory ratio inactive * ------------------------------------- * 10MB 1 5MB * 100MB 1 50MB * 1GB 3 250MB * 10GB 10 0.9GB * 100GB 31 3GB * 1TB 101 10GB * 10TB 320 32GB It would be possible to apply the same precise ratios when determining the limit for radix tree nodes containing shadow entries, but since it is merely an approximation of the oldest refault distances in the wild and the code also makes assumptions about the node population density, keep it simple and always target the full cache size. While at it, clarify the comment and the formula for memory footprint. Link: http://lkml.kernel.org/r/20161117214701.29000-1-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: 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: workingset: restore refault tracking for single-page filesJohannes Weiner2016-12-131-8/+1
| | | | | | | | | | | | | | | | | | | | | | | Shadow entries in the page cache used to be accounted behind the radix tree implementation's back in the upper bits of node->count, and the radix tree code extending a single-entry tree with a shadow entry in root->rnode would corrupt that counter. As a result, we could not put shadow entries at index 0 if the tree didn't have any other entries, and that means no refault detection for any single-page file. Now that the shadow entries are tracked natively in the radix tree's exceptional counter, this is no longer necessary. Extending and shrinking the tree from and to single entries in root->rnode now does the right thing when the entry is exceptional, remove that limitation. Link: http://lkml.kernel.org/r/20161117193244.GF23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: workingset: move shadow entry tracking to radix tree exceptional trackingJohannes Weiner2016-12-136-138/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, we track the shadow entries in the page cache in the upper bits of the radix_tree_node->count, behind the back of the radix tree implementation. Because the radix tree code has no awareness of them, we rely on random subtleties throughout the implementation (such as the node->count != 1 check in the shrinking code, which is meant to exclude multi-entry nodes but also happens to skip nodes with only one shadow entry, as that's accounted in the upper bits). This is error prone and has, in fact, caused the bug fixed in d3798ae8c6f3 ("mm: filemap: don't plant shadow entries without radix tree node"). To remove these subtleties, this patch moves shadow entry tracking from the upper bits of node->count to the existing counter for exceptional entries. node->count goes back to being a simple counter of valid entries in the tree node and can be shrunk to a single byte. This vastly simplifies the page cache code. All accounting happens natively inside the radix tree implementation, and maintaining the LRU linkage of shadow nodes is consolidated into a single function in the workingset code that is called for leaf nodes affected by a change in the page cache tree. This also removes the last user of the __radix_delete_node() return value. Eliminate it. Link: http://lkml.kernel.org/r/20161117193211.GE23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: radix-tree: update callback for changing leaf nodesJohannes Weiner2016-12-134-16/+36
| | | | | | | | | | | | | | | | | | | Support handing __radix_tree_replace() a callback that gets invoked for all leaf nodes that change or get freed as a result of the slot replacement, to assist users tracking nodes with node->private_list. This prepares for putting page cache shadow entries into the radix tree root again and drastically simplifying the shadow tracking. Link: http://lkml.kernel.org/r/20161117193134.GD23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: radix-tree: add entry deletion support to __radix_tree_replace()Johannes Weiner2016-12-131-111/+116
| | | | | | | | | | | | | | | | | | | Page cache shadow entry handling will be a lot simpler when it can use a single generic replacement function for pages, shadow entries, and emptying slots. Make __radix_tree_replace() properly account insertions and deletions in node->count and garbage collect nodes as they become empty. Then re-implement radix_tree_delete() on top of it. Link: http://lkml.kernel.org/r/20161117193058.GC23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: radix-tree: check accounting of existing slot replacement usersJohannes Weiner2016-12-1310-40/+64
| | | | | | | | | | | | | | | | | | | | | | | | The bug in khugepaged fixed earlier in this series shows that radix tree slot replacement is fragile; and it will become more so when not only NULL<->!NULL transitions need to be caught but transitions from and to exceptional entries as well. We need checks. Re-implement radix_tree_replace_slot() on top of the sanity-checked __radix_tree_replace(). This requires existing callers to also pass the radix tree root, but it'll warn us when somebody replaces slots with contents that need proper accounting (transitions between NULL entries, real entries, exceptional entries) and where a replacement through the slot pointer would corrupt the radix tree node counts. Link: http://lkml.kernel.org/r/20161117193021.GB23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* lib: radix-tree: native accounting of exceptional entriesJohannes Weiner2016-12-134-12/+57
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The way the page cache is sneaking shadow entries of evicted pages into the radix tree past the node entry accounting and tracking them manually in the upper bits of node->count is fraught with problems. These shadow entries are marked in the tree as exceptional entries, which are a native concept to the radix tree. Maintain an explicit counter of exceptional entries in the radix tree node. Subsequent patches will switch shadow entry tracking over to that counter. DAX and shmem are the other users of exceptional entries. Since slot replacements that change the entry type from regular to exceptional must now be accounted, introduce a __radix_tree_replace() function that does replacement and accounting, and switch DAX and shmem over. The increase in radix tree node size is temporary. A followup patch switches the shadow tracking to this new scheme and we'll no longer need the upper bits in node->count and shrink that back to one byte. Link: http://lkml.kernel.org/r/20161117192945.GA23430@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: workingset: turn shadow node shrinker bugs into warningsJohannes Weiner2016-12-131-8/+12
| | | | | | | | | | | | | | | | | | When the shadow page shrinker tries to reclaim a radix tree node but finds it in an unexpected state - it should contain no pages, and non-zero shadow entries - there is no need to kill the executing task or even the entire system. Warn about the invalid state, then leave that tree node be. Simply don't put it back on the shadow LRU for future reclaim and move on. Link: http://lkml.kernel.org/r/20161117191138.22769-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: khugepaged: fix radix tree node leak in shmem collapse error pathJohannes Weiner2016-12-131-2/+4
| | | | | | | | | | | | | | | | | | | | The radix tree counts valid entries in each tree node. Entries stored in the tree cannot be removed by simpling storing NULL in the slot or the internal counters will be off and the node never gets freed again. When collapsing a shmem page fails, restore the holes that were filled with radix_tree_insert() with a proper radix tree deletion. Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages") Link: http://lkml.kernel.org/r/20161117191138.22769-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: khugepaged: close use-after-free race during shmem collapsingJohannes Weiner2016-12-131-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm: workingset: radix tree subtleties & single-page file refaults", v3. This is another revision of the radix tree / workingset patches based on feedback from Jan and Kirill. This is a follow-up to d3798ae8c6f3 ("mm: filemap: don't plant shadow entries without radix tree node"). That patch fixed an issue that was caused mainly by the page cache sneaking special shadow page entries into the radix tree and relying on subtleties in the radix tree code to make that work. The fix also had to stop tracking refaults for single-page files because shadow pages stored as direct pointers in radix_tree_root->rnode weren't properly handled during tree extension. These patches make the radix tree code explicitely support and track such special entries, to eliminate the subtleties and to restore the thrash detection for single-page files. This patch (of 9): When a radix tree iteration drops the tree lock, another thread might swoop in and free the node holding the current slot. The iteration needs to do another tree lookup from the current index to continue. [kirill.shutemov@linux.intel.com: re-lookup for replacement] Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages") Link: http://lkml.kernel.org/r/20161117191138.22769-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <mawilcox@linuxonhyperv.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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