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![Tejun Heo](/assets/img/avatar_default.png)
percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
298 lines
8.8 KiB
C
298 lines
8.8 KiB
C
/*
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* linux/mm/mmu_notifier.c
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*
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* Copyright (C) 2008 Qumranet, Inc.
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* Copyright (C) 2008 SGI
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* Christoph Lameter <clameter@sgi.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/rculist.h>
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#include <linux/mmu_notifier.h>
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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/*
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* This function can't run concurrently against mmu_notifier_register
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* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
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* runs with mm_users == 0. Other tasks may still invoke mmu notifiers
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* in parallel despite there being no task using this mm any more,
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* through the vmas outside of the exit_mmap context, such as with
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* vmtruncate. This serializes against mmu_notifier_unregister with
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* the mmu_notifier_mm->lock in addition to RCU and it serializes
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* against the other mmu notifiers with RCU. struct mmu_notifier_mm
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* can't go away from under us as exit_mmap holds an mm_count pin
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* itself.
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*/
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void __mmu_notifier_release(struct mm_struct *mm)
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{
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struct mmu_notifier *mn;
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spin_lock(&mm->mmu_notifier_mm->lock);
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while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
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mn = hlist_entry(mm->mmu_notifier_mm->list.first,
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struct mmu_notifier,
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hlist);
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/*
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* We arrived before mmu_notifier_unregister so
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* mmu_notifier_unregister will do nothing other than
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* to wait ->release to finish and
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* mmu_notifier_unregister to return.
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*/
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hlist_del_init_rcu(&mn->hlist);
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/*
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* RCU here will block mmu_notifier_unregister until
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* ->release returns.
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*/
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rcu_read_lock();
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spin_unlock(&mm->mmu_notifier_mm->lock);
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/*
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* if ->release runs before mmu_notifier_unregister it
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* must be handled as it's the only way for the driver
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* to flush all existing sptes and stop the driver
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* from establishing any more sptes before all the
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* pages in the mm are freed.
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*/
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if (mn->ops->release)
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mn->ops->release(mn, mm);
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rcu_read_unlock();
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spin_lock(&mm->mmu_notifier_mm->lock);
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}
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spin_unlock(&mm->mmu_notifier_mm->lock);
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/*
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* synchronize_rcu here prevents mmu_notifier_release to
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* return to exit_mmap (which would proceed freeing all pages
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* in the mm) until the ->release method returns, if it was
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* invoked by mmu_notifier_unregister.
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*
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* The mmu_notifier_mm can't go away from under us because one
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* mm_count is hold by exit_mmap.
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*/
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synchronize_rcu();
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}
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/*
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* If no young bitflag is supported by the hardware, ->clear_flush_young can
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* unmap the address and return 1 or 0 depending if the mapping previously
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* existed or not.
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*/
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int __mmu_notifier_clear_flush_young(struct mm_struct *mm,
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unsigned long address)
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{
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struct mmu_notifier *mn;
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struct hlist_node *n;
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int young = 0;
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rcu_read_lock();
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hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
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if (mn->ops->clear_flush_young)
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young |= mn->ops->clear_flush_young(mn, mm, address);
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}
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rcu_read_unlock();
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return young;
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}
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void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address,
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pte_t pte)
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{
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struct mmu_notifier *mn;
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struct hlist_node *n;
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rcu_read_lock();
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hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
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if (mn->ops->change_pte)
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mn->ops->change_pte(mn, mm, address, pte);
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/*
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* Some drivers don't have change_pte,
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* so we must call invalidate_page in that case.
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*/
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else if (mn->ops->invalidate_page)
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mn->ops->invalidate_page(mn, mm, address);
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}
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rcu_read_unlock();
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}
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void __mmu_notifier_invalidate_page(struct mm_struct *mm,
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unsigned long address)
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{
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struct mmu_notifier *mn;
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struct hlist_node *n;
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rcu_read_lock();
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hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
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if (mn->ops->invalidate_page)
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mn->ops->invalidate_page(mn, mm, address);
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}
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rcu_read_unlock();
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}
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void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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struct mmu_notifier *mn;
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struct hlist_node *n;
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rcu_read_lock();
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hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
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if (mn->ops->invalidate_range_start)
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mn->ops->invalidate_range_start(mn, mm, start, end);
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}
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rcu_read_unlock();
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}
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void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
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unsigned long start, unsigned long end)
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{
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struct mmu_notifier *mn;
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struct hlist_node *n;
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rcu_read_lock();
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hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) {
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if (mn->ops->invalidate_range_end)
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mn->ops->invalidate_range_end(mn, mm, start, end);
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}
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rcu_read_unlock();
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}
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static int do_mmu_notifier_register(struct mmu_notifier *mn,
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struct mm_struct *mm,
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int take_mmap_sem)
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{
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struct mmu_notifier_mm *mmu_notifier_mm;
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int ret;
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BUG_ON(atomic_read(&mm->mm_users) <= 0);
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ret = -ENOMEM;
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mmu_notifier_mm = kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
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if (unlikely(!mmu_notifier_mm))
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goto out;
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if (take_mmap_sem)
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down_write(&mm->mmap_sem);
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ret = mm_take_all_locks(mm);
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if (unlikely(ret))
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goto out_cleanup;
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if (!mm_has_notifiers(mm)) {
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INIT_HLIST_HEAD(&mmu_notifier_mm->list);
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spin_lock_init(&mmu_notifier_mm->lock);
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mm->mmu_notifier_mm = mmu_notifier_mm;
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mmu_notifier_mm = NULL;
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}
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atomic_inc(&mm->mm_count);
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/*
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* Serialize the update against mmu_notifier_unregister. A
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* side note: mmu_notifier_release can't run concurrently with
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* us because we hold the mm_users pin (either implicitly as
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* current->mm or explicitly with get_task_mm() or similar).
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* We can't race against any other mmu notifier method either
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* thanks to mm_take_all_locks().
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*/
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spin_lock(&mm->mmu_notifier_mm->lock);
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hlist_add_head(&mn->hlist, &mm->mmu_notifier_mm->list);
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spin_unlock(&mm->mmu_notifier_mm->lock);
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mm_drop_all_locks(mm);
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out_cleanup:
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if (take_mmap_sem)
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up_write(&mm->mmap_sem);
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/* kfree() does nothing if mmu_notifier_mm is NULL */
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kfree(mmu_notifier_mm);
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out:
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BUG_ON(atomic_read(&mm->mm_users) <= 0);
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return ret;
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}
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/*
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* Must not hold mmap_sem nor any other VM related lock when calling
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* this registration function. Must also ensure mm_users can't go down
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* to zero while this runs to avoid races with mmu_notifier_release,
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* so mm has to be current->mm or the mm should be pinned safely such
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* as with get_task_mm(). If the mm is not current->mm, the mm_users
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* pin should be released by calling mmput after mmu_notifier_register
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* returns. mmu_notifier_unregister must be always called to
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* unregister the notifier. mm_count is automatically pinned to allow
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* mmu_notifier_unregister to safely run at any time later, before or
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* after exit_mmap. ->release will always be called before exit_mmap
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* frees the pages.
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*/
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int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
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{
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return do_mmu_notifier_register(mn, mm, 1);
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}
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EXPORT_SYMBOL_GPL(mmu_notifier_register);
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/*
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* Same as mmu_notifier_register but here the caller must hold the
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* mmap_sem in write mode.
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*/
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int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
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{
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return do_mmu_notifier_register(mn, mm, 0);
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}
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EXPORT_SYMBOL_GPL(__mmu_notifier_register);
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/* this is called after the last mmu_notifier_unregister() returned */
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void __mmu_notifier_mm_destroy(struct mm_struct *mm)
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{
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BUG_ON(!hlist_empty(&mm->mmu_notifier_mm->list));
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kfree(mm->mmu_notifier_mm);
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mm->mmu_notifier_mm = LIST_POISON1; /* debug */
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}
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/*
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* This releases the mm_count pin automatically and frees the mm
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* structure if it was the last user of it. It serializes against
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* running mmu notifiers with RCU and against mmu_notifier_unregister
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* with the unregister lock + RCU. All sptes must be dropped before
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* calling mmu_notifier_unregister. ->release or any other notifier
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* method may be invoked concurrently with mmu_notifier_unregister,
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* and only after mmu_notifier_unregister returned we're guaranteed
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* that ->release or any other method can't run anymore.
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*/
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void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
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{
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BUG_ON(atomic_read(&mm->mm_count) <= 0);
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spin_lock(&mm->mmu_notifier_mm->lock);
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if (!hlist_unhashed(&mn->hlist)) {
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hlist_del_rcu(&mn->hlist);
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/*
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* RCU here will force exit_mmap to wait ->release to finish
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* before freeing the pages.
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*/
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rcu_read_lock();
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spin_unlock(&mm->mmu_notifier_mm->lock);
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/*
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* exit_mmap will block in mmu_notifier_release to
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* guarantee ->release is called before freeing the
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* pages.
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*/
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if (mn->ops->release)
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mn->ops->release(mn, mm);
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rcu_read_unlock();
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} else
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spin_unlock(&mm->mmu_notifier_mm->lock);
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/*
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* Wait any running method to finish, of course including
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* ->release if it was run by mmu_notifier_relase instead of us.
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*/
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synchronize_rcu();
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BUG_ON(atomic_read(&mm->mm_count) <= 0);
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mmdrop(mm);
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}
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EXPORT_SYMBOL_GPL(mmu_notifier_unregister);
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