kernel/linux.git/mm/mmu_notifier.c, branch linux-4.7.y

fix Christoph's email addresses

2016-03-17T22:09:34+00:00

There are various email addresses for me throughout the kernel. Use the one that will always be valid. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mmu-notifier: add clear_young callback

2015-09-10T20:29:01+00:00

In the scope of the idle memory tracking feature, which is introduced by the following patch, we need to clear the referenced/accessed bit not only in primary, but also in secondary ptes. The latter is required in order to estimate wss of KVM VMs. At the same time we want to avoid flushing tlb, because it is quite expensive and it won't really affect the final result. Currently, there is no function for clearing pte young bit that would meet our requirements, so this patch introduces one. To achieve that we have to add a new mmu-notifier callback, clear_young, since there is no method for testing-and-clearing a secondary pte w/o flushing tlb. The new method is not mandatory and currently only implemented by KVM. Signed-off-by: Vladimir Davydov Reviewed-by: Andres Lagar-Cavilla Acked-by: Paolo Bonzini Cc: Minchan Kim Cc: Raghavendra K T Cc: Johannes Weiner Cc: Michal Hocko Cc: Greg Thelen Cc: Michel Lespinasse Cc: David Rientjes Cc: Pavel Emelyanov Cc: Cyrill Gorcunov Cc: Jonathan Corbet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mmu_notifier: add the callback for mmu_notifier_invalidate_range()

2014-11-13T02:46:09+00:00

Now that the mmu_notifier_invalidate_range() calls are in place, add the callback to allow subsystems to register against it. Signed-off-by: Joerg Roedel Reviewed-by: Andrea Arcangeli Reviewed-by: Jérôme Glisse Cc: Peter Zijlstra Cc: Rik van Riel Cc: Hugh Dickins Cc: Mel Gorman Cc: Johannes Weiner Cc: Jay Cornwall Cc: Oded Gabbay Cc: Suravee Suthikulpanit Cc: Jesse Barnes Cc: David Woodhouse Signed-off-by: Andrew Morton Signed-off-by: Oded Gabbay

kvm: Fix page ageing bugs

2014-09-24T12:07:58+00:00

1. We were calling clear_flush_young_notify in unmap_one, but we are within an mmu notifier invalidate range scope. The spte exists no more (due to range_start) and the accessed bit info has already been propagated (due to kvm_pfn_set_accessed). Simply call clear_flush_young. 2. We clear_flush_young on a primary MMU PMD, but this may be mapped as a collection of PTEs by the secondary MMU (e.g. during log-dirty). This required expanding the interface of the clear_flush_young mmu notifier, so a lot of code has been trivially touched. 3. In the absence of shadow_accessed_mask (e.g. EPT A bit), we emulate the access bit by blowing the spte. This requires proper synchronizing with MMU notifier consumers, like every other removal of spte's does. Signed-off-by: Andres Lagar-Cavilla Acked-by: Rik van Riel Signed-off-by: Paolo Bonzini

mmu_notifier: add call_srcu and sync function for listener to delay call and sync

2014-08-07T01:01:22+00:00

When kernel device drivers or subsystems want to bind their lifespan to t= he lifespan of the mm_struct, they usually use one of the following methods: 1. Manually calling a function in the interested kernel module. The funct= ion call needs to be placed in mmput. This method was rejected by several ker= nel maintainers. 2. Registering to the mmu notifier release mechanism. The problem with the latter approach is that the mmu_notifier_release cal= lback is called from__mmu_notifier_release (called from exit_mmap). That functi= on iterates over the list of mmu notifiers and don't expect the release call= back function to remove itself from the list. Therefore, the callback function= in the kernel module can't release the mmu_notifier_object, which is actuall= y the kernel module's object itself. As a result, the destruction of the kernel module's object must to be done in a delayed fashion. This patch adds support for this delayed callback, by adding a new mmu_notifier_call_srcu function that receives a function ptr and calls th= at function with call_srcu. In that function, the kernel module releases its object. To use mmu_notifier_call_srcu, the calling module needs to call b= efore that a new function called mmu_notifier_unregister_no_release that as its= name implies, unregisters a notifier without calling its notifier release call= back. This patch also adds a function that will call barrier_srcu so those kern= el modules can sync with mmu_notifier. Signed-off-by: Peter Zijlstra Signed-off-by: Jérôme Glisse Signed-off-by: Oded Gabbay Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: audit/fix non-modular users of module_init in core code

2014-01-24T00:36:52+00:00

Code that is obj-y (always built-in) or dependent on a bool Kconfig (built-in or absent) can never be modular. So using module_init as an alias for __initcall can be somewhat misleading. Fix these up now, so that we can relocate module_init from init.h into module.h in the future. If we don't do this, we'd have to add module.h to obviously non-modular code, and that would be a worse thing. The audit targets the following module_init users for change: mm/ksm.c bool KSM mm/mmap.c bool MMU mm/huge_memory.c bool TRANSPARENT_HUGEPAGE mm/mmu_notifier.c bool MMU_NOTIFIER Note that direct use of __initcall is discouraged, vs. one of the priority categorized subgroups. As __initcall gets mapped onto device_initcall, our use of subsys_initcall (which makes sense for these files) will thus change this registration from level 6-device to level 4-subsys (i.e. slightly earlier). However no observable impact of that difference has been observed during testing. One might think that core_initcall (l2) or postcore_initcall (l3) would be more appropriate for anything in mm/ but if we look at some actual init functions themselves, we see things like: mm/huge_memory.c --> hugepage_init --> hugepage_init_sysfs mm/mmap.c --> init_user_reserve --> sysctl_user_reserve_kbytes mm/ksm.c --> ksm_init --> sysfs_create_group and hence the choice of subsys_initcall (l4) seems reasonable, and at the same time minimizes the risk of changing the priority too drastically all at once. We can adjust further in the future. Also, several instances of missing ";" at EOL are fixed. Signed-off-by: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: relase -> release

2013-06-28T12:34:33+00:00

Signed-off-by: Geert Uytterhoeven Signed-off-by: Jiri Kosina

mm: mmu_notifier: re-fix freed page still mapped in secondary MMU

2013-05-24T23:22:51+00:00

Commit 751efd8610d3 ("mmu_notifier_unregister NULL Pointer deref and multiple ->release()") breaks the fix 3ad3d901bbcf ("mm: mmu_notifier: fix freed page still mapped in secondary MMU"). Since hlist_for_each_entry_rcu() is changed now, we can not revert that patch directly, so this patch reverts the commit and simply fix the bug spotted by that patch This bug spotted by commit 751efd8610d3 is: There is a race condition between mmu_notifier_unregister() and __mmu_notifier_release(). Assume two tasks, one calling mmu_notifier_unregister() as a result of a filp_close() ->flush() callout (task A), and the other calling mmu_notifier_release() from an mmput() (task B). A B t1 srcu_read_lock() t2 if (!hlist_unhashed()) t3 srcu_read_unlock() t4 srcu_read_lock() t5 hlist_del_init_rcu() t6 synchronize_srcu() t7 srcu_read_unlock() t8 hlist_del_rcu() <--- NULL pointer deref. This can be fixed by using hlist_del_init_rcu instead of hlist_del_rcu. The another issue spotted in the commit is "multiple ->release() callouts", we needn't care it too much because it is really rare (e.g, can not happen on kvm since mmu-notify is unregistered after exit_mmap()) and the later call of multiple ->release should be fast since all the pages have already been released by the first call. Anyway, this issue should be fixed in a separate patch. -stable suggestions: Any version that has commit 751efd8610d3 need to be backported. I find the oldest version has this commit is 3.0-stable. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Xiao Guangrong Tested-by: Robin Holt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

hlist: drop the node parameter from iterators

2013-02-28T03:10:24+00:00

I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin Acked-by: Paul E. McKenney Signed-off-by: Sasha Levin Cc: Wu Fengguang Cc: Marcelo Tosatti Cc: Gleb Natapov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: export mmu notifier invalidates

2013-02-24T01:50:23+00:00

We at SGI have a need to address some very high physical address ranges with our GRU (global reference unit), sometimes across partitioned machine boundaries and sometimes with larger addresses than the cpu supports. We do this with the aid of our own 'extended vma' module which mimics the vma. When something (either unmap or exit) frees an 'extended vma' we use the mmu notifiers to clean them up. We had been able to mimic the functions __mmu_notifier_invalidate_range_start() and __mmu_notifier_invalidate_range_end() by locking the per-mm lock and walking the per-mm notifier list. But with the change to a global srcu lock (static in mmu_notifier.c) we can no longer do that. Our module has no access to that lock. So we request that these two functions be exported. Signed-off-by: Cliff Wickman Acked-by: Robin Holt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds