- May 20, 2016
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Stephen Rothwell authored
Signed-off-by:Stephen Rothwell <sfr@canb.auug.org.au>
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Stephen Rothwell authored
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Jiri Slaby authored
With VT=n, the kernel build fails with: drivers/built-in.o: In function `kgdboc_pre_exp_handler': kgdboc.c:(.text+0x7b5aa): undefined reference to `fg_console' kgdboc.c:(.text+0x7b5ce): undefined reference to `vc_cons' kgdboc.c:(.text+0x7b5d5): undefined reference to `vc_cons' kgdboc.o is built when KGDB_SERIAL_CONSOLE is set. So make KGDB_SERIAL_CONSOLE depend on HW_CONSOLE which includes those symbols. Link: http://lkml.kernel.org/r/1459412955-4696-1-git-send-email-jslaby@suse.cz Signed-off-by:
Jiri Slaby <jslaby@suse.cz> Reported-by:
"Jim Davis" <jim.epost@gmail.com> Acked-by:
Jason Wessel <jason.wessel@windriver.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Arnd Bergmann authored
The newly added failure path in amdgpu_mn_get() use the wrong return type: drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c: In function 'amdgpu_mn_get': drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c:237:10: error: return makes pointer from integer without a cast This adds the necessary ERR_PTR() conversion. Fixes: ad35eee9 ("drm/amdgpu: make amdgpu_mn_get wait for mmap_sem killable") Signed-off-by:
Arnd Bergmann <arnd@arndb.de> Acked-by:
Michal Hocko <mhocko@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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Michal Hocko authored
amdgpu_mn_get which is called during ioct path relies on mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
Vlastimil Babka <vbabka@suse.cz> Reviewed-by:
Christian König <christian.koenig@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Alex Deucher <alexander.deucher@amd.com> Signed-off-by:
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Michal Hocko authored
radeon_mn_get which is called during ioct path relies on mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
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Michal Hocko authored
i915_gem_mmap_ioctl relies on mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
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Michal Hocko authored
xol_add_vma needs mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Do not warn in dup_xol_work if __create_xol_area failed due to fatal signal pending because this is usually considered a kernel issue. Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Acked-by:
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Michal Hocko authored
PR_SET_THP_DISABLE requires mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
Alex Thorlton <athorlton@sgi.com> Signed-off-by:
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Michal Hocko authored
setup_arg_pages requires mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. All the callers are already handling error path and the fatal signal doesn't need any additional treatment. The same applies to __bprm_mm_init. Signed-off-by:
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Michal Hocko authored
aio_setup_ring waits for mmap_sem in writable mode. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. This will also expedite the return to the userspace and do_exit. Signed-off-by:
Jeff Moyer <jmoyer@redhat.com> Acked-by:
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Michal Hocko authored
coredump_wait waits for mmap_sem for write currently which can prevent oom_reaper to reclaim the oom victims address space asynchronously because that requires mmap_sem for read. This might happen if the oom victim is multi threaded and some thread(s) is holding mmap_sem for read (e.g. page fault) and it is stuck in the page allocator while other thread(s) reached coredump_wait already. This patch simply uses down_write_killable and bails out with EINTR if the lock got interrupted by the fatal signal. do_coredump will return right away and do_group_exit will take care to zap the whole thread group. Signed-off-by:
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Michal Hocko authored
most architectures are relying on mmap_sem for write in their arch_setup_additional_pages. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
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Michal Hocko authored
shmat and shmdt rely on mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
Davidlohr Bueso <dave@stgolabs.net> Acked-by:
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Michal Hocko authored
dup_mmap needs to lock current's mm mmap_sem for write. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by:
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Michal Hocko authored
CLEAR_REFS_MM_HIWATER_RSS and CLEAR_REFS_SOFT_DIRTY are relying on mmap_sem for write. If the waiting task gets killed by the oom killer and it would operate on the current's mm it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. This will also expedite the return to the userspace and do_exit even if the mm is remote. Signed-off-by:
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Michal Hocko authored
Now that all the callers handle vm_brk failure we can change it wait for mmap_sem killable to help oom_reaper to not get blocked just because vm_brk gets blocked behind mmap_sem readers. Signed-off-by:
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Michal Hocko authored
load_elf_library doesn't handle vm_brk failure although nothing really indicates it cannot do that because the function is allowed to fail due to vm_mmap failures already. This might be not a problem now but later patch will make vm_brk killable (resp. mmap_sem for write waiting will become killable) and so the failure will be more probable. Signed-off-by:
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Michal Hocko authored
vm_brk is allowed to fail but load_aout_binary simply ignores the error and happily continues. I haven't noticed any problem from that in real life but later patches will make the failure more likely because vm_brk will become killable (resp. mmap_sem for write waiting will become killable) so we should be more careful now. The error handling should be quite straightforward because there are calls to vm_mmap which check the error properly already. The only notable exception is set_brk which is called after beyond_if label. But nothing indicates that we cannot move it above set_binfmt as the two do not depend on each other and fail before we do set_binfmt and alter reference counting. Signed-off-by:
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Michal Hocko authored
Almost all current users of vm_munmap are ignoring the return value and so they do not handle potential error. This means that some VMAs might stay behind. This patch doesn't try to solve those potential problems. Quite contrary it adds a new failure mode by using down_write_killable in vm_munmap. This should be safer than other failure modes, though, because the process is guaranteed to die as soon as it leaves the kernel and exit_mmap will clean the whole address space. This will help in the OOM conditions when the oom victim might be stuck waiting for the mmap_sem for write which in turn can block oom_reaper which relies on the mmap_sem for read to make a forward progress and reclaim the address space of the victim. Signed-off-by:
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Michal Hocko authored
All the callers of vm_mmap seem to check for the failure already and bail out in one way or another on the error which means that we can change it to use killable version of vm_mmap_pgoff and return -EINTR if the current task gets killed while waiting for mmap_sem. This also means that vm_mmap_pgoff can be killable by default and drop the additional parameter. This will help in the OOM conditions when the oom victim might be stuck waiting for the mmap_sem for write which in turn can block oom_reaper which relies on the mmap_sem for read to make a forward progress and reclaim the address space of the victim. Please note that load_elf_binary is ignoring vm_mmap error for current->personality & MMAP_PAGE_ZERO case but that shouldn't be a problem because the address is not used anywhere and we never return to the userspace if we got killed. Signed-off-by:
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Michal Hocko authored
This is a follow up work for oom_reaper [1]. As the async OOM killing depends on oom_sem for read we would really appreciate if a holder for write didn't stood in the way. This patchset is changing many of down_write calls to be killable to help those cases when the writer is blocked and waiting for readers to release the lock and so help __oom_reap_task to process the oom victim. Most of the patches are really trivial because the lock is help from a shallow syscall paths where we can return EINTR trivially and allow the current task to die (note that EINTR will never get to the userspace as the task has fatal signal pending). Others seem to be easy as well as the callers are already handling fatal errors and bail and return to userspace which should be sufficient to handle the failure gracefully. I am not familiar with all those code paths so a deeper review is really appreciated. As this work is touching more areas which are not directly connected I have tried to keep the CC list as small as possible and people who I believed would be familiar are CCed only to the specific patches (all should have received the cover though). This patchset is based on linux-next and it depends on down_write_killable for rw_semaphores which got merged into tip locking/rwsem branch and it is merged into this next tree. I guess it would be easiest to route these patches via mmotm because of the dependency on the tip tree but if respective maintainers prefer other way I have no objections. I haven't covered all the mmap_write(mm->mmap_sem) instances here $ git grep "down_write(.*\<mmap_sem\>)" next/master | wc -l 98 $ git grep "down_write(.*\<mmap_sem\>)" | wc -l 62 I have tried to cover those which should be relatively easy to review in this series because this alone should be a nice improvement. Other places can be changed on top. [0] http://lkml.kernel.org/r/1456752417-9626-1-git-send-email-mhocko@kernel.org [1] http://lkml.kernel.org/r/1452094975-551-1-git-send-email-mhocko@kernel.org [2] http://lkml.kernel.org/r/1456750705-7141-1-git-send-email-mhocko@kernel.org This patch (of 18): This is the first step in making mmap_sem write waiters killable. It focuses on the trivial ones which are taking the lock early after entering the syscall and they are not changing state before. Therefore it is very easy to change them to use down_write_killable and immediately return with -EINTR. This will allow the waiter to pass away without blocking the mmap_sem which might be required to make a forward progress. E.g. the oom reaper will need the lock for reading to dismantle the OOM victim address space. The only tricky function in this patch is vm_mmap_pgoff which has many call sites via vm_mmap. To reduce the risk keep vm_mmap with the original non-killable semantic for now. vm_munmap callers do not bother checking the return value so open code it into the munmap syscall path for now for simplicity. Signed-off-by:
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Andrew Morton authored
This cast is no longer needed. Cc: Johannes Berg <johannes.berg@intel.com> Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com> Cc: Intel Linux Wireless <linuxwifi@intel.com> Cc: Kalle Valo <kvalo@codeaurora.org> Signed-off-by: -
Stephen Rothwell authored
Link: http://lkml.kernel.org/r/20160502183234.1dad8115@canb.auug.org.au Signed-off-by:
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by:
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- May 19, 2016
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Stephen Rothwell authored
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Stephen Rothwell authored
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Stephen Rothwell authored
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Stephen Rothwell authored
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Stephen Rothwell authored
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Stephen Rothwell authored
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Yogesh Gaur authored
Avoid waking up every thread sleeping in a msgrcv call during suspend and resume by calling a freezable blocking call. Previous patches modified the freezer to avoid sending wakeups to threads that are blocked in freezable blocking calls. Ref: https://lkml.org/lkml/2013/5/1/424 Backtrace: [<c03e3924>] (__schedule+0x0/0x5d8) from [<c03e3f88>] (schedule+0x8c/0x90) [<c03e3efc>] (schedule+0x0/0x90) from [<c01ef9f8>] (do_msgrcv+0x2e0/0x368) [<c01ef718>] (do_msgrcv+0x0/0x368) from [<c01efaac>] (SyS_msgrcv+0x2c/0x38) [<c01efa80>] (SyS_msgrcv+0x0/0x38) from [<c001a180>] (ret_fast_syscall+0x0/0x48) tPlay0Cb2 R running 0 297 204 0x00000001 This call was selected to be converted to a freezable call because it doesn't hold any locks or release any resources when interrupted that might be needed by another freezing task or a kernel driver during suspend, and is a common site where idle userspace tasks are blocked. Signed-off-by:
Yogesh Gaur <yn.gaur@samsung.com> Signed-off-by:
Manjeet Pawar <manjeet.p@samsung.com> Signed-off-by:
Maninder Singh <maninder1.s@samsung.com> Reviewed-by : Ajeet Yadav <ajeet.y@samsung.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:
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Maninder Singh authored
When any task is stuck in Interruptible or Uninterruptible state then waking up of that task fails. If wakeup fails, then suspend operation fails and all process send to frezeer state at this moment also gets wakeup. Correct implementation is that if suspend fails, then kernel would retry suspend operation again after some specific timeinterval for some fixed retry count. But as changes suggested by Mr Colin Cross (https://lkml.org/lkml/2013/5/1/424 ), for the system calls for which issue has been faced process flag being appended with PF_FREEZER_SKIP. We are testing some scenarios in which we have to do multi suspend-resume scenario, and we faced the problem, hence the suggested changes for msgsnd and msgrcv. Avoid waking up every thread sleeping in a msgsnd call during suspend and resume by calling a freezable blocking call. Previous patches modified the freezer to avoid sending wakeups to threads that are blocked in freezable blocking calls. This call was selected to be converted to a freezable call because it doesn't hold any locks or release any resources when interrupted that might be needed by another freezing task or a kernel driver during suspend, and is a common site where idle userspace tasks are blocked. Signed-off-by:
Vaneet narang <v.narang@samsung.com> Signed-off-by:
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Manfred Spraul authored
Commit 6d07b68c ("ipc/sem.c: optimize sem_lock()") introduced a race: sem_lock has a fast path that allows parallel simple operations. There are two reasons why a simple operation cannot run in parallel: - a non-simple operations is ongoing (sma->sem_perm.lock held) - a complex operation is sleeping (sma->complex_count != 0) As both facts are stored independently, a thread can bypass the current checks by sleeping in the right positions. See below for more details (or kernel bugzilla 105651). The patch fixes that by creating one variable (complex_mode) that tracks both reasons why parallel operations are not possible. The patch also updates stale documentation regarding the locking. With regards to stable kernels: The patch is required for all kernels that include the commit 6d07b68c ("ipc/sem.c: optimize sem_lock()") (3.10?) The alternative is to revert the patch that introduced the race. Background: Here is the race of the current implementation: Thread A: (simple op) - does the first "sma->complex_count == 0" test Thread B: (complex op) - does sem_lock(): This includes an array scan. But the scan can't find Thread A, because Thread A does not own sem->lock yet. - the thread does the operation, increases complex_count, drops sem_lock, sleeps Thread A: - spin_lock(&sem->lock), spin_is_locked(sma->sem_perm.lock) - sleeps before the complex_count test Thread C: (complex op) - does sem_lock (no array scan, complex_count==1) - wakes up Thread B. - decrements complex_count Thread A: - does the complex_count test Bug: Now both thread A and thread C operate on the same array, without any synchronization. Fixes: 6d07b68c ("ipc/sem.c: optimize sem_lock()") Signed-off-by:
Manfred Spraul <manfred@colorfullife.com> Reported-by:
<felixh@informatik.uni-bremen.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: <stable@vger.kernel.org> Signed-off-by:
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Kieran Bingham authored
Add myself as a co-maintainer for scripts/gdb supporting Jan Kizka Link: http://lkml.kernel.org/r/fb5d34ce563f33d2f324f26f592b24ded30032ee.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
Kieran Bingham <kieran@bingham.xyz> Signed-off-by:
Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by:
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Kieran Bingham authored
The recent fixes to lx-dmesg, now allow the command to print successfully on Python3, however the python interpreter wraps the bytes for each line with a b'<text>' marker. To remove this, we need to decode the line, where .decode() will default to 'UTF-8' Link: http://lkml.kernel.org/r/d67ccf93f2479c94cb3399262b9b796e0dbefcf2.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
Dom Cote <buzdelabuz2@gmail.com> Tested-by:
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Dom Cote authored
When built against Python 3, GDB differs in the return type for its read_memory function, causing the lx-dmesg command to fail. Now that we have an improved read_16() we can use the new read_memoryview() abstraction to make lx-dmesg return valid data on both current Python APIs Tested with python 3.4 and 2.7 Tested with gdb 7.7 Link: http://lkml.kernel.org/r/28477b727ff7fe3101fd4e426060e8a68317a639.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
Dom Cote <buzdelabuz2+git@gmail.com> [kieran@bingham.xyz: Adjusted commit log to better reflect code changes] Tested-by: Kieran Bingham <kieran@bingham.xyz> (Py2.7,Py3.4,GDB10) Signed-off-by:
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Dom Cote authored
Change the read_u16 function so it accepts both 'str' and 'byte' as type for the arguments. When calling read_memory() from gdb API, depending on if it was built with 2.7 or 3.X, the format used to return the data will differ ( 'str' for 2.7, and 'byte' for 3.X ). Add a function read_memoryview() to be able to get a 'memoryview' object back from read_memory() both with python 2.7 and 3.X . Tested with python 3.4 and 2.7 Tested with gdb 7.7 Link: http://lkml.kernel.org/r/73621f564503137a002a639d174e4fb35f73f462.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
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Kieran Bingham authored
The tasks module already provides helpers to find the task struct by pid, and the thread_info by task struct; however this is cumbersome to utilise on the gdb commandline. Wrap these two functionalities together in an extra single helper to allow exploring the thread info, from a PID value Link: http://lkml.kernel.org/r/dadc5667f053ec811eb3e3033d99d937fedbc93b.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
Kieran Bingham <kieran.bingham@linaro.org> Signed-off-by:
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Kieran Bingham authored
Provide a worked example for utilising the lx_radix_tree_lookup function Link: http://lkml.kernel.org/r/e786008ac5aec4b84198812805b326d718bdeb4b.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
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Kieran Bingham authored
Linux makes use of the Radix Tree data structure to store pointers indexed by integer values. This structure is utilised across many structures in the kernel including the IRQ descriptor tables, and several filesystems. This module provides a method to lookup values from a structure given its head node. Usage: The function lx_radix_tree_lookup, must be given a symbol of type struct radix_tree_root, and an index into that tree. The object returned is a generic integer value, and must be cast correctly to the type based on the storage in the data structure. For example, to print the irq descriptor in the sparse irq_desc_tree at index 18, try the following: (gdb) print (struct irq_desc)$lx_radix_tree_lookup(irq_desc_tree, 18) Link: http://lkml.kernel.org/r/d2028c55e50cf95a9b7f8ca0d11885174b0cc709.1462865983.git.jan.kiszka@siemens.com Signed-off-by:
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