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2020-04-02mm/hugetlb.c: clean code by removing unnecessary initializationMateusz Nosek
Previously variable 'check_addr' was initialized, but was not read later before reassigning. So the initialization can be removed. Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Link: http://lkml.kernel.org/r/20200303212354.25226-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb: support file_region coalescing againMina Almasry
An earlier patch in this series disabled file_region coalescing in order to hang the hugetlb_cgroup uncharge info on the file_region entries. This patch re-adds support for coalescing of file_region entries. Essentially everytime we add an entry, we call a recursive function that tries to coalesce the added region with the regions next to it. The worst case call depth for this function is 3: one to coalesce with the region next to it, one to coalesce to the region prev, and one to reach the base case. This is an important performance optimization as private mappings add their entries page by page, and we could incur big performance costs for large mappings with lots of file_region entries in their resv_map. [almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs] Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com [almasrymina@google.com: remove check_coalesce_bug debug code] Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb_cgroup: support noreserve mappingsMina Almasry
Support MAP_NORESERVE accounting as part of the new counter. For each hugepage allocation, at allocation time we check if there is a reservation for this allocation or not. If there is a reservation for this allocation, then this allocation was charged at reservation time, and we don't re-account it. If there is no reserevation for this allocation, we charge the appropriate hugetlb_cgroup. The hugetlb_cgroup to uncharge for this allocation is stored in page[3].private. We use new APIs added in an earlier patch to set this pointer. Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-6-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb_cgroup: add accounting for shared mappingsMina Almasry
For shared mappings, the pointer to the hugetlb_cgroup to uncharge lives in the resv_map entries, in file_region->reservation_counter. After a call to region_chg, we charge the approprate hugetlb_cgroup, and if successful, we pass on the hugetlb_cgroup info to a follow up region_add call. When a file_region entry is added to the resv_map via region_add, we put the pointer to that cgroup in file_region->reservation_counter. If charging doesn't succeed, we report the error to the caller, so that the kernel fails the reservation. On region_del, which is when the hugetlb memory is unreserved, we also uncharge the file_region->reservation_counter. [akpm@linux-foundation.org: forward declare struct file_region] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-5-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb: disable region_add file_region coalescingMina Almasry
A follow up patch in this series adds hugetlb cgroup uncharge info the file_region entries in resv->regions. The cgroup uncharge info may differ for different regions, so they can no longer be coalesced at region_add time. So, disable region coalescing in region_add in this patch. Behavior change: Say a resv_map exists like this [0->1], [2->3], and [5->6]. Then a region_chg/add call comes in region_chg/add(f=0, t=5). Old code would generate resv->regions: [0->5], [5->6]. New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], [5->6]. Special care needs to be taken to handle the resv->adds_in_progress variable correctly. In the past, only 1 region would be added for every region_chg and region_add call. But now, each call may add multiple regions, so we can no longer increment adds_in_progress by 1 in region_chg, or decrement adds_in_progress by 1 after region_add or region_abort. Instead, region_chg calls add_reservation_in_range() to count the number of regions needed and allocates those, and that info is passed to region_add and region_abort to decrement adds_in_progress correctly. We've also modified the assumption that region_add after region_chg never fails. region_chg now pre-allocates at least 1 region for region_add. If region_add needs more regions than region_chg has allocated for it, then it may fail. [almasrymina@google.com: fix file_region entry allocations] Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Greg Thelen <gthelen@google.com> Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb_cgroup: add reservation accounting for private mappingsMina Almasry
Normally the pointer to the cgroup to uncharge hangs off the struct page, and gets queried when it's time to free the page. With hugetlb_cgroup reservations, this is not possible. Because it's possible for a page to be reserved by one task and actually faulted in by another task. The best place to put the hugetlb_cgroup pointer to uncharge for reservations is in the resv_map. But, because the resv_map has different semantics for private and shared mappings, the code patch to charge/uncharge shared and private mappings is different. This patch implements charging and uncharging for private mappings. For private mappings, the counter to uncharge is in resv_map->reservation_counter. On initializing the resv_map this is set to NULL. On reservation of a region in private mapping, the tasks hugetlb_cgroup is charged and the hugetlb_cgroup is placed is resv_map->reservation_counter. On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter. [akpm@linux-foundation.org: forward declare struct resv_map] Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/hugetlb_cgroup: fix hugetlb_cgroup migrationMina Almasry
Commit c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations") mistakingly doesn't handle the migration of *both* the reservation hugetlb_cgroup and the fault hugetlb_cgroup correctly. What should happen is that both cgroups shuold be queried from the old page, then both set to NULL on the old page, then both inserted into the new page. The mistake also creates the following warning: mm/hugetlb_cgroup.c: In function 'hugetlb_cgroup_migrate': mm/hugetlb_cgroup.c:777:25: warning: variable 'h_cg' set but not used [-Wunused-but-set-variable] struct hugetlb_cgroup *h_cg; ^~~~ Solution is to add the missing steps, namly setting the reservation hugetlb_cgroup to NULL on the old page, and setting the fault hugetlb_cgroup on the new page. Fixes: c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations") Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200218194727.46995-1-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb_cgroup: add interface for charge/uncharge hugetlb reservationsMina Almasry
Augments hugetlb_cgroup_charge_cgroup to be able to charge hugetlb usage or hugetlb reservation counter. Adds a new interface to uncharge a hugetlb_cgroup counter via hugetlb_cgroup_uncharge_counter. Integrates the counter with hugetlb_cgroup, via hugetlb_cgroup_init, hugetlb_cgroup_have_usage, and hugetlb_cgroup_css_offline. Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Link: http://lkml.kernel.org/r/20200211213128.73302-2-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlb_cgroup: add hugetlb_cgroup reservation counterMina Almasry
These counters will track hugetlb reservations rather than hugetlb memory faulted in. This patch only adds the counter, following patches add the charging and uncharging of the counter. This is patch 1 of an 9 patch series. Problem: Currently tasks attempting to reserve more hugetlb memory than is available get a failure at mmap/shmget time. This is thanks to Hugetlbfs Reservations [1]. However, if a task attempts to reserve more hugetlb memory than its hugetlb_cgroup limit allows, the kernel will allow the mmap/shmget call, but will SIGBUS the task when it attempts to fault in the excess memory. We have users hitting their hugetlb_cgroup limits and thus we've been looking at this failure mode. We'd like to improve this behavior such that users violating the hugetlb_cgroup limits get an error on mmap/shmget time, rather than getting SIGBUS'd when they try to fault the excess memory in. This gives the user an opportunity to fallback more gracefully to non-hugetlbfs memory for example. The underlying problem is that today's hugetlb_cgroup accounting happens at hugetlb memory *fault* time, rather than at *reservation* time. Thus, enforcing the hugetlb_cgroup limit only happens at fault time, and the offending task gets SIGBUS'd. Proposed Solution: A new page counter named 'hugetlb.xMB.rsvd.[limit|usage|max_usage]_in_bytes'. This counter has slightly different semantics than 'hugetlb.xMB.[limit|usage|max_usage]_in_bytes': - While usage_in_bytes tracks all *faulted* hugetlb memory, rsvd.usage_in_bytes tracks all *reserved* hugetlb memory and hugetlb memory faulted in without a prior reservation. - If a task attempts to reserve more memory than limit_in_bytes allows, the kernel will allow it to do so. But if a task attempts to reserve more memory than rsvd.limit_in_bytes, the kernel will fail this reservation. This proposal is implemented in this patch series, with tests to verify functionality and show the usage. Alternatives considered: 1. A new cgroup, instead of only a new page_counter attached to the existing hugetlb_cgroup. Adding a new cgroup seemed like a lot of code duplication with hugetlb_cgroup. Keeping hugetlb related page counters under hugetlb_cgroup seemed cleaner as well. 2. Instead of adding a new counter, we considered adding a sysctl that modifies the behavior of hugetlb.xMB.[limit|usage]_in_bytes, to do accounting at reservation time rather than fault time. Adding a new page_counter seems better as userspace could, if it wants, choose to enforce different cgroups differently: one via limit_in_bytes, and another via rsvd.limit_in_bytes. This could be very useful if you're transitioning how hugetlb memory is partitioned on your system one cgroup at a time, for example. Also, someone may find usage for both limit_in_bytes and rsvd.limit_in_bytes concurrently, and this approach gives them the option to do so. Testing: - Added tests passing. - Used libhugetlbfs for regression testing. [1]: https://www.kernel.org/doc/html/latest/vm/hugetlbfs_reserv.html Signed-off-by: Mina Almasry <almasrymina@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Link: http://lkml.kernel.org/r/20200211213128.73302-1-almasrymina@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlbfs: Use i_mmap_rwsem to address page fault/truncate raceMike Kravetz
hugetlbfs page faults can race with truncate and hole punch operations. Current code in the page fault path attempts to handle this by 'backing out' operations if we encounter the race. One obvious omission in the current code is removing a page newly added to the page cache. This is pretty straight forward to address, but there is a more subtle and difficult issue of backing out hugetlb reservations. To handle this correctly, the 'reservation state' before page allocation needs to be noted so that it can be properly backed out. There are four distinct possibilities for reservation state: shared/reserved, shared/no-resv, private/reserved and private/no-resv. Backing out a reservation may require memory allocation which could fail so that needs to be taken into account as well. Instead of writing the required complicated code for this rare occurrence, just eliminate the race. i_mmap_rwsem is now held in read mode for the duration of page fault processing. Hold i_mmap_rwsem in write mode when modifying i_size. In this way, truncation can not proceed when page faults are being processed. In addition, i_size will not change during fault processing so a single check can be made to ensure faults are not beyond (proposed) end of file. Faults can still race with hole punch, but that race is handled by existing code and the use of hugetlb_fault_mutex. With this modification, checks for races with truncation in the page fault path can be simplified and removed. remove_inode_hugepages no longer needs to take hugetlb_fault_mutex in the case of truncation. Comments are expanded to explain reasoning behind locking. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-3-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronizationMike Kravetz
Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2. While discussing the issue with huge_pte_offset [1], I remembered that there were more outstanding hugetlb races. These issues are: 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become invalid via a call to huge_pmd_unshare by another thread. 2) hugetlbfs page faults can race with truncation causing invalid global reserve counts and state. A previous attempt was made to use i_mmap_rwsem in this manner as described at [2]. However, those patches were reverted starting with [3] due to locking issues. To effectively use i_mmap_rwsem to address the above issues it needs to be held (in read mode) during page fault processing. However, during fault processing we need to lock the page we will be adding. Lock ordering requires we take page lock before i_mmap_rwsem. Waiting until after taking the page lock is too late in the fault process for the synchronization we want to do. To address this lock ordering issue, the following patches change the lock ordering for hugetlb pages. This is not too invasive as hugetlbfs processing is done separate from core mm in many places. However, I don't really like this idea. Much ugliness is contained in the new routine hugetlb_page_mapping_lock_write() of patch 1. The only other way I can think of to address these issues is by catching all the races. After catching a race, cleanup, backout, retry ... etc, as needed. This can get really ugly, especially for huge page reservations. At one time, I started writing some of the reservation backout code for page faults and it got so ugly and complicated I went down the path of adding synchronization to avoid the races. Any other suggestions would be welcome. [1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/ [2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/ [3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com [4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/ [5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/ This patch (of 2): While looking at BUGs associated with invalid huge page map counts, it was discovered and observed that a huge pte pointer could become 'invalid' and point to another task's page table. Consider the following: A task takes a page fault on a shared hugetlbfs file and calls huge_pte_alloc to get a ptep. Suppose the returned ptep points to a shared pmd. Now, another task truncates the hugetlbfs file. As part of truncation, it unmaps everyone who has the file mapped. If the range being truncated is covered by a shared pmd, huge_pmd_unshare will be called. For all but the last user of the shared pmd, huge_pmd_unshare will clear the pud pointing to the pmd. If the task in the middle of the page fault is not the last user, the ptep returned by huge_pte_alloc now points to another task's page table or worse. This leads to bad things such as incorrect page map/reference counts or invalid memory references. To fix, expand the use of i_mmap_rwsem as follows: - i_mmap_rwsem is held in read mode whenever huge_pmd_share is called. huge_pmd_share is only called via huge_pte_alloc, so callers of huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers of huge_pte_alloc continue to hold the semaphore until finished with the ptep. - i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called. One problem with this scheme is that it requires taking i_mmap_rwsem before taking the page lock during page faults. This is not the order specified in the rest of mm code. Handling of hugetlbfs pages is mostly isolated today. Therefore, we use this alternative locking order for PageHuge() pages. mapping->i_mmap_rwsem hugetlb_fault_mutex (hugetlbfs specific page fault mutex) page->flags PG_locked (lock_page) To help with lock ordering issues, hugetlb_page_mapping_lock_write() is introduced to write lock the i_mmap_rwsem associated with a page. In most cases it is easy to get address_space via vma->vm_file->f_mapping. However, in the case of migration or memory errors for anon pages we do not have an associated vma. A new routine _get_hugetlb_page_mapping() will use anon_vma to get address_space in these cases. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Prakash Sangappa <prakash.sangappa@oracle.com> Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/memblock.c: remove redundant assignment to variable max_addrColin Ian King
The variable max_addr is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and can be removed. Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Link: http://lkml.kernel.org/r/20200228235003.112718-1-colin.king@canonical.com Addresses-Coverity: ("Unused value") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: mempolicy: require at least one nodeid for MPOL_PREFERREDRandy Dunlap
Using an empty (malformed) nodelist that is not caught during mount option parsing leads to a stack-out-of-bounds access. The option string that was used was: "mpol=prefer:,". However, MPOL_PREFERRED requires a single node number, which is not being provided here. Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's nodeid. Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display") Reported-by: Entropy Moe <3ntr0py1337@gmail.com> Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: mempolicy: use VM_BUG_ON_VMA in queue_pages_test_walk()Yang Shi
The VM_BUG_ON() is already used by queue_pages_test_walk(), it sounds better to dump more debug information by using VM_BUG_ON_VMA() to help debugging. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: "Li Xinhai" <lixinhai.lxh@gmail.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/1579068565-110432-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/mempolicy: check hugepage migration is supported by arch in vma_migratable()Li Xinhai
vma_migratable() is called to check if pages in vma can be migrated before go ahead to further actions. Currently it is used in below code path: - task_numa_work - mbind - move_pages For hugetlb mapping, whether vma is migratable or not is determined by: - CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION - arch_hugetlb_migration_supported Issue: current code only checks for CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION alone, and no code should use it directly. (note that current code in vma_migratable don't cause failure or bug because unmap_and_move_huge_page() will catch unsupported hugepage and handle it properly) This patch checks the two factors by hugepage_migration_supported for impoving code logic and robustness. It will enable early bail out of hugepage migration procedure, but because currently all architecture supporting hugepage migration is able to support all page size, we would not see performance gain with this patch applied. vma_migratable() is moved to mm/mempolicy.c, because of the circular reference of mempolicy.h and hugetlb.h cause defining it as inline not feasible. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Link: http://lkml.kernel.org/r/1579786179-30633-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/mempolicy: support MPOL_MF_STRICT for huge page mappingLi Xinhai
MPOL_MF_STRICT is used in mbind() for purposes: (1) MPOL_MF_STRICT is set alone without MPOL_MF_MOVE or MPOL_MF_MOVE_ALL, to check if there is misplaced page and return -EIO; (2) MPOL_MF_STRICT is set with MPOL_MF_MOVE or MPOL_MF_MOVE_ALL, to check if there is misplaced page which is failed to isolate, or page is success on isolate but failed to move, and return -EIO. For non hugepage mapping, (1) and (2) are implemented as expectation. For hugepage mapping, (1) is not implemented. And in (2), the part about failed to isolate and report -EIO is not implemented. This patch implements the missed parts for hugepage mapping. Benefits with it applied: - User space can apply same code logic to handle mbind() on hugepage and non hugepage mapping; - Reliably using MPOL_MF_STRICT alone to check whether there is misplaced page or not when bind policy on address range, especially for address range which contains both hugepage and non hugepage mapping. Analysis of potential impact to existing users: - If MPOL_MF_STRICT alone was previously used, hugetlb pages not following the memory policy would not cause an EIO error. After this change, hugetlb pages are treated like all other pages. If MPOL_MF_STRICT alone is used and hugetlb pages do not follow memory policy an EIO error will be returned. - For users who using MPOL_MF_STRICT with MPOL_MF_MOVE or MPOL_MF_MOVE_ALL, the semantic about some pages could not be moved will not be changed by this patch, because failed to isolate and failed to move have same effects to users, so their existing code will not be impacted. In mbind man page, the note about 'MPOL_MF_STRICT is ignored on huge page mappings' can be removed after this patch is applied. Mike: : The current behavior with MPOL_MF_STRICT and hugetlb pages is inconsistent : and does not match documentation (as described above). The special : behavior for hugetlb pages ideally should have been removed when hugetlb : page migration was introduced. It is unlikely that anyone relies on : today's inconsistent behavior, and removing one more case of special : handling for hugetlb pages is a good thing. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: linux-man <linux-man@vger.kernel.org> Link: http://lkml.kernel.org/r/1581559627-6206-1-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/compaction.c: clean code by removing unnecessary assignmentMateusz Nosek
Previously 0 was assigned to variable 'last_migrated_pfn'. But the variable is not read after that, so the assignment can be removed. Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Link: http://lkml.kernel.org/r/20200318174509.15021-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/compaction: Disable compact_unevictable_allowed on RTSebastian Andrzej Siewior
Since commit 5bbe3547aa3ba ("mm: allow compaction of unevictable pages") it is allowed to examine mlocked pages and compact them by default. On -RT even minor pagefaults are problematic because it may take a few 100us to resolve them and until then the task is blocked. Make compact_unevictable_allowed = 0 default and issue a warning on RT if it is changed. [bigeasy@linutronix.de: v5] Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@linutronix.de/ Link: http://lkml.kernel.org/r/20200319165536.ovi75tsr2seared4@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@linutronix.de/ Link: http://lkml.kernel.org/r/20200303202225.nhqc3v5gwlb7x6et@linutronix.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm, compaction: fully assume capture is not NULL in compact_zone_order()Vlastimil Babka
Dan reports: The patch 5e1f0f098b46: "mm, compaction: capture a page under direct compaction" from Mar 5, 2019, leads to the following Smatch complaint: mm/compaction.c:2321 compact_zone_order() error: we previously assumed 'capture' could be null (see line 2313) mm/compaction.c 2288 static enum compact_result compact_zone_order(struct zone *zone, int order, 2289 gfp_t gfp_mask, enum compact_priority prio, 2290 unsigned int alloc_flags, int classzone_idx, 2291 struct page **capture) ^^^^^^^ 2313 if (capture) ^^^^^^^ Check for NULL 2314 current->capture_control = &capc; 2315 2316 ret = compact_zone(&cc, &capc); 2317 2318 VM_BUG_ON(!list_empty(&cc.freepages)); 2319 VM_BUG_ON(!list_empty(&cc.migratepages)); 2320 2321 *capture = capc.page; ^^^^^^^^ Unchecked dereference. 2322 current->capture_control = NULL; 2323 In practice this is not an issue, as the only caller path passes non-NULL capture: __alloc_pages_direct_compact() struct page *page = NULL; try_to_compact_pages(capture = &page); compact_zone_order(capture = capture); So let's remove the unnecessary check, which should also make Smatch happy. Fixes: 5e1f0f098b46 ("mm, compaction: capture a page under direct compaction") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Link: http://lkml.kernel.org/r/18b0df3c-0589-d96c-23fa-040798fee187@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm,thp,compaction,cma: allow THP migration for CMA allocationsRik van Riel
The code to implement THP migrations already exists, and the code for CMA to clear out a region of memory already exists. Only a few small tweaks are needed to allow CMA to move THP memory when attempting an allocation from alloc_contig_range. With these changes, migrating THPs from a CMA area works when allocating a 1GB hugepage from CMA memory. [riel@surriel.com: fix hugetlbfs pages per Mike, cleanup per Vlastimil] Link: http://lkml.kernel.org/r/20200228104700.0af2f18d@imladris.surriel.com Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200227213238.1298752-2-riel@surriel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm,compaction,cma: add alloc_contig flag to compact_controlRik van Riel
Patch series "fix THP migration for CMA allocations", v2. Transparent huge pages are allocated with __GFP_MOVABLE, and can end up in CMA memory blocks. Transparent huge pages also have most of the infrastructure in place to allow migration. However, a few pieces were missing, causing THP migration to fail when attempting to use CMA to allocate 1GB hugepages. With these patches in place, THP migration from CMA blocks seems to work, both for anonymous THPs and for tmpfs/shmem THPs. This patch (of 2): Add information to struct compact_control to indicate that the allocator would really like to clear out this specific part of memory, used by for example CMA. Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Cc: Joonsoo Kim <js1304@gmail.com> Link: http://lkml.kernel.org/r/20200227213238.1298752-1-riel@surriel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vmscan.c: do_try_to_free_pages(): clean code by removing unnecessary ↵Mateusz Nosek
assignment sc->memcg_low_skipped resets skipped_deactivate to 0 but this is not needed as this code path is never reachable with skipped_deactivate != 0 due to previous sc->skipped_deactivate branch. [mhocko@kernel.org: rewrite changelog] Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Link: http://lkml.kernel.org/r/20200319165938.23354-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vmscan.c: make may_enter_fs bool in shrink_page_list()Kirill Tkhai
This gives some size improvement: $size mm/vmscan.o (before) text data bss dec hex filename 53670 24123 12 77805 12fed mm/vmscan.o $size mm/vmscan.o (after) text data bss dec hex filename 53648 24123 12 77783 12fd7 mm/vmscan.o Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/Message-ID: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vmscan.c: clean code by removing unnecessary assignmentMateusz Nosek
Previously 0 was assigned to variable 'lruvec_size', but the variable was never read later. So the assignment can be removed. Fixes: f87bccde6a7d ("mm/vmscan: remove unused lru_pages argument") Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: David Hildenbrand <david@redhat.com> Link: http://lkml.kernel.org/r/20200229214022.11853-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vmscan.c: fix data races using kswapd_classzone_idxQian Cai
pgdat->kswapd_classzone_idx could be accessed concurrently in wakeup_kswapd(). Plain writes and reads without any lock protection result in data races. Fix them by adding a pair of READ|WRITE_ONCE() as well as saving a branch (compilers might well optimize the original code in an unintentional way anyway). While at it, also take care of pgdat->kswapd_order and non-kswapd threads in allow_direct_reclaim(). The data races were reported by KCSAN, BUG: KCSAN: data-race in wakeup_kswapd / wakeup_kswapd write to 0xffff9f427ffff2dc of 4 bytes by task 7454 on cpu 13: wakeup_kswapd+0xf1/0x400 wakeup_kswapd at mm/vmscan.c:3967 wake_all_kswapds+0x59/0xc0 wake_all_kswapds at mm/page_alloc.c:4241 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_slowpath at mm/page_alloc.c:4512 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 1 lock held by mtest01/7454: #0: ffff9f425afe8808 (&mm->mmap_sem#2){++++}, at: do_page_fault+0x143/0x6f9 do_user_addr_fault at arch/x86/mm/fault.c:1405 (inlined by) do_page_fault at arch/x86/mm/fault.c:1539 irq event stamp: 6944085 count_memcg_event_mm+0x1a6/0x270 count_memcg_event_mm+0x119/0x270 __do_softirq+0x34c/0x57c irq_exit+0xa2/0xc0 read to 0xffff9f427ffff2dc of 4 bytes by task 7472 on cpu 38: wakeup_kswapd+0xc8/0x400 wake_all_kswapds+0x59/0xc0 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 1 lock held by mtest01/7472: #0: ffff9f425a9ac148 (&mm->mmap_sem#2){++++}, at: do_page_fault+0x143/0x6f9 irq event stamp: 6793561 count_memcg_event_mm+0x1a6/0x270 count_memcg_event_mm+0x119/0x270 __do_softirq+0x34c/0x57c irq_exit+0xa2/0xc0 BUG: KCSAN: data-race in kswapd / wakeup_kswapd write to 0xffff90973ffff2dc of 4 bytes by task 820 on cpu 6: kswapd+0x27c/0x8d0 kthread+0x1e0/0x200 ret_from_fork+0x27/0x50 read to 0xffff90973ffff2dc of 4 bytes by task 6299 on cpu 0: wakeup_kswapd+0xf3/0x450 wake_all_kswapds+0x59/0xc0 __alloc_pages_slowpath+0xdcc/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Matthew Wilcox <willy@infradead.org> Link: http://lkml.kernel.org/r/1582749472-5171-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vmscan.c: remove cpu online notification for nowWei Yang
kswapd kernel thread starts either with a CPU affinity set to the full cpu mask of its target node or without any affinity at all if the node is CPUless. There is a cpu hotplug callback (kswapd_cpu_online) that implements an elaborate way to update this mask when a cpu is onlined. It is not really clear whether there is any actual benefit from this scheme. Completely CPU-less NUMA nodes rarely gain a new CPU during runtime. Drop the code for that reason. If there is a real usecase then we can resurrect and simplify the code. [mhocko@suse.com rewrite changelog] Suggested-by: Michal Hocko <mhocko@suse.org> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/20200218224422.3407-1-richardw.yang@linux.intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: vmscan: replace open codings to NUMA_NO_NODEYang Shi
The commit 98fa15f34cb3 ("mm: replace all open encodings for NUMA_NO_NODE") did the replacement across the kernel tree, but we got some more in vmscan.c since then. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/1581568298-45317-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: vmpressure: use mem_cgroup_is_root APIYang Shi
Use mem_cgroup_is_root() API to check if memcg is root memcg instead of open coding. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/1581398649-125989-2-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: vmpressure: don't need call kfree if kstrndup failsYang Shi
When kstrndup fails, no memory was allocated and we can exit directly. [david@redhat.com: reword changelog] Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Link: http://lkml.kernel.org/r/1581398649-125989-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/page_alloc: simplify page_is_buddy() for better code readabilitychenqiwu
Simplify page_is_buddy() to reduce the redundant code for better code readability. Signed-off-by: chenqiwu <chenqiwu@xiaomi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/1583853751-5525-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/page_alloc.c: micro-optimisation Remove unnecessary branchMateusz Nosek
Previously if branch condition was false, the assignment was not executed. The assignment can be safely executed even when the condition is false and it is not incorrect as it assigns the value of 'nodemask' to 'ac.nodemask' which already has the same value. So as the assignment can be executed unconditionally, the branch can be removed. Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Link: http://lkml.kernel.org/r/20200307225335.31300-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/page_alloc.c: use free_area_empty() instead of open-codingchenqiwu
Use free_area_empty() API to replace list_empty() for better code readability. Signed-off-by: chenqiwu <chenqiwu@xiaomi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Link: http://lkml.kernel.org/r/1583674354-7713-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm, pagealloc: micro-optimisation: save two branches on hot page allocation pathMateusz Nosek
This patch makes ALLOC_KSWAPD equal to __GFP_KSWAPD_RECLAIM (cast to int). Thanks to that code like: if (gfp_mask & __GFP_KSWAPD_RECLAIM) alloc_flags |= ALLOC_KSWAPD; can be changed to: alloc_flags |= (__force int) (gfp_mask &__GFP_KSWAPD_RECLAIM); Thanks to this one branch less is generated in the assembly. In case of ALLOC_KSWAPD flag two branches are saved, first one in code that always executes in the beginning of page allocation and the second one in loop in page allocator slowpath. Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Link: http://lkml.kernel.org/r/20200304162118.14784-1-mateusznosek0@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/page_alloc: increase default min_free_kbytes boundJoel Savitz
Currently, the vm.min_free_kbytes sysctl value is capped at a hardcoded 64M in init_per_zone_wmark_min (unless it is overridden by khugepaged initialization). This value has not been modified since 2005, and enterprise-grade systems now frequently have hundreds of GB of RAM and multiple 10, 40, or even 100 GB NICs. We have seen page allocation failures on heavily loaded systems related to NIC drivers. These issues were resolved by an increase to vm.min_free_kbytes. This patch increases the hardcoded value by a factor of 4 as a temporary solution. Further work to make the calculation of vm.min_free_kbytes more consistent throughout the kernel would be desirable. As an example of the inconsistency of the current method, this value is recalculated by init_per_zone_wmark_min() in the case of memory hotplug which will override the value set by set_recommended_min_free_kbytes() called during khugepaged initialization even if khugepaged remains enabled, however an on/off toggle of khugepaged will then recalculate and set the value via set_recommended_min_free_kbytes(). Signed-off-by: Joel Savitz <jsavitz@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Rafael Aquini <aquini@redhat.com> Link: http://lkml.kernel.org/r/20200220150103.5183-1-jsavitz@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02kasan: detect negative size in memory operation functionWalter Wu
Patch series "fix the missing underflow in memory operation function", v4. The patchset helps to produce a KASAN report when size is negative in memory operation functions. It is helpful for programmer to solve an undefined behavior issue. Patch 1 based on Dmitry's review and suggestion, patch 2 is a test in order to verify the patch 1. [1]https://bugzilla.kernel.org/show_bug.cgi?id=199341 [2]https://lore.kernel.org/linux-arm-kernel/20190927034338.15813-1-walter-zh.wu@mediatek.com/ This patch (of 2): KASAN missed detecting size is a negative number in memset(), memcpy(), and memmove(), it will cause out-of-bounds bug. So needs to be detected by KASAN. If size is a negative number, then it has a reason to be defined as out-of-bounds bug type. Casting negative numbers to size_t would indeed turn up as a large size_t and its value will be larger than ULONG_MAX/2, so that this can qualify as out-of-bounds. KASAN report is shown below: BUG: KASAN: out-of-bounds in kmalloc_memmove_invalid_size+0x70/0xa0 Read of size 18446744073709551608 at addr ffffff8069660904 by task cat/72 CPU: 2 PID: 72 Comm: cat Not tainted 5.4.0-rc1-next-20191004ajb-00001-gdb8af2f372b2-dirty #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x288 show_stack+0x14/0x20 dump_stack+0x10c/0x164 print_address_description.isra.9+0x68/0x378 __kasan_report+0x164/0x1a0 kasan_report+0xc/0x18 check_memory_region+0x174/0x1d0 memmove+0x34/0x88 kmalloc_memmove_invalid_size+0x70/0xa0 [1] https://bugzilla.kernel.org/show_bug.cgi?id=199341 [cai@lca.pw: fix -Wdeclaration-after-statement warn] Link: http://lkml.kernel.org/r/1583509030-27939-1-git-send-email-cai@lca.pw [peterz@infradead.org: fix objtool warning] Link: http://lkml.kernel.org/r/20200305095436.GV2596@hirez.programming.kicks-ass.net Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Link: http://lkml.kernel.org/r/20191112065302.7015-1-walter-zh.wu@mediatek.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/sparse.c: allocate memmap preferring the given nodeBaoquan He
When allocating memmap for hot added memory with the classic sparse, the specified 'nid' is ignored in populate_section_memmap(). While in allocating memmap for the classic sparse during boot, the node given by 'nid' is preferred. And VMEMMAP prefers the node of 'nid' in both boot stage and memory hot adding. So seems no reason to not respect the node of 'nid' for the classic sparse when hot adding memory. Use kvmalloc_node instead to use the passed in 'nid'. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/20200316125625.GH3486@MiWiFi-R3L-srv Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/sparse.c: use kvmalloc/kvfree to alloc/free memmap for the classic sparseBaoquan He
This change makes populate_section_memmap()/depopulate_section_memmap much simpler. Suggested-by: Michal Hocko <mhocko@kernel.org> Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200316125450.GG3486@MiWiFi-R3L-srv Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/sparse: rename pfn_present() to pfn_in_present_section()Pingfan Liu
After introducing mem sub section concept, pfn_present() loses its literal meaning, and will not be necessary a truth on partial populated mem section. Since all of the callers use it to judge an absent section, it is better to rename pfn_present() as pfn_in_present_section(). Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Cc: Dan Williams <dan.j.williams@intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Leonardo Bras <leonardo@linux.ibm.com> Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com> Cc: Nathan Lynch <nathanl@linux.ibm.com> Link: http://lkml.kernel.org/r/1581919110-29575-1-git-send-email-kernelfans@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/sparsemem: get address to page struct instead of address to pfnWei Yang
memmap should be the address to page struct instead of address to pfn. As mentioned by David, if system memory and devmem sit within a section, the mismatch address would lead kdump to dump unexpected memory. Since sub-section only works for SPARSEMEM_VMEMMAP, pfn_to_page() is valid to get the page struct address at this point. Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Hildenbrand <david@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Baoquan He <bhe@redhat.com> Link: http://lkml.kernel.org/r/20200210005048.10437-1-richardw.yang@linux.intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/mremap: add MREMAP_DONTUNMAP to mremap()Brian Geffon
When remapping an anonymous, private mapping, if MREMAP_DONTUNMAP is set, the source mapping will not be removed. The remap operation will be performed as it would have been normally by moving over the page tables to the new mapping. The old vma will have any locked flags cleared, have no pagetables, and any userfaultfds that were watching that range will continue watching it. For a mapping that is shared or not anonymous, MREMAP_DONTUNMAP will cause the mremap() call to fail. Because MREMAP_DONTUNMAP always results in moving a VMA you MUST use the MREMAP_MAYMOVE flag, it's not possible to resize a VMA while also moving with MREMAP_DONTUNMAP so old_len must always be equal to the new_len otherwise it will return -EINVAL. We hope to use this in Chrome OS where with userfaultfd we could write an anonymous mapping to disk without having to STOP the process or worry about VMA permission changes. This feature also has a use case in Android, Lokesh Gidra has said that "As part of using userfaultfd for GC, We'll have to move the physical pages of the java heap to a separate location. For this purpose mremap will be used. Without the MREMAP_DONTUNMAP flag, when I mremap the java heap, its virtual mapping will be removed as well. Therefore, we'll require performing mmap immediately after. This is not only time consuming but also opens a time window where a native thread may call mmap and reserve the java heap's address range for its own usage. This flag solves the problem." [bgeffon@google.com: v6] Link: http://lkml.kernel.org/r/20200218173221.237674-1-bgeffon@google.com [bgeffon@google.com: v7] Link: http://lkml.kernel.org/r/20200221174248.244748-1-bgeffon@google.com Signed-off-by: Brian Geffon <bgeffon@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Lokesh Gidra <lokeshgidra@google.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Michael S . Tsirkin" <mst@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Will Deacon <will@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Jesse Barnes <jsbarnes@google.com> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Florian Weimer <fweimer@redhat.com> Link: http://lkml.kernel.org/r/20200207201856.46070-1-bgeffon@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: mmap: add trace point of vm_unmapped_areaJaewon Kim
Even on 64 bit kernel, the mmap failure can happen for a 32 bit task. Virtual memory space shortage of a task on mmap is reported to userspace as -ENOMEM. It can be confused as physical memory shortage of overall system. The vm_unmapped_area can be called to by some drivers or other kernel core system like filesystem. In my platform, GPU driver calls to vm_unmapped_area and the driver returns -ENOMEM even in GPU side shortage. It can be hard to distinguish which code layer returns the -ENOMEM. Create mmap trace file and add trace point of vm_unmapped_area. i.e.) 277.156599: vm_unmapped_area: addr=77e0d03000 err=0 total_vm=0x17014b flags=0x1 len=0x400000 lo=0x8000 hi=0x7878c27000 mask=0x0 ofs=0x1 342.838740: vm_unmapped_area: addr=0 err=-12 total_vm=0xffb08 flags=0x0 len=0x100000 lo=0x40000000 hi=0xfffff000 mask=0x0 ofs=0x22 [akpm@linux-foundation.org: prefix address printk with 0x, per Matthew] Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@suse.de> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michel Lespinasse <walken@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200320055823.27089-3-jaewon31.kim@samsung.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mmap: remove inline of vm_unmapped_areaJaewon Kim
Patch series "mm: mmap: add mmap trace point", v3. Create mmap trace file and add trace point of vm_unmapped_area(). This patch (of 2): In preparation for next patch remove inline of vm_unmapped_area and move code to mmap.c. There is no logical change. Also remove unmapped_area[_topdown] out of mm.h, there is no code calling to them. Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michel Lespinasse <walken@google.com> Cc: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/20200320055823.27089-2-jaewon31.kim@samsung.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/memory.c: clarify a confusing comment for vm_iomap_memoryWang Wenhu
The param "start" actually referes to the physical memory start, which is to be mapped into virtual area vma. And it is the field vma->vm_start which stands for the start of the area. Most of the time, we do not read through whole implementation of a function but only the definition and essential comments. Accurate comments are definitely the base stone. Signed-off-by: Wang Wenhu <wenhu.wang@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200318052206.105104-1-wenhu.wang@vivo.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: clarify a confusing comment for remap_pfn_range()WANG Wenhu
It really made me scratch my head. Replace the comment with an accurate and consistent description. The parameter pfn actually refers to the page frame number which is right-shifted by PAGE_SHIFT from the physical address. Signed-off-by: WANG Wenhu <wenhu.wang@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200310073955.43415-1-wenhu.wang@vivo.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: allow to react to fatal signalsPeter Xu
The existing gup code does not react to the fatal signals in many code paths. For example, in one retry path of gup we're still using down_read() rather than down_read_killable(). Also, when doing page faults we don't pass in FAULT_FLAG_KILLABLE as well, which means that within the faulting process we'll wait in non-killable way as well. These were spotted by Linus during the code review of some other patches. Let's allow the gup code to react to fatal signals to improve the responsiveness of threads when during gup and being killed. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220160256.9887-1-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: allow VM_FAULT_RETRY for multiple timesPeter Xu
This is the gup counterpart of the change that allows the VM_FAULT_RETRY to happen for more than once. One thing to mention is that we must check the fatal signal here before retry because the GUP can be interrupted by that, otherwise we can loop forever. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220195357.16371-1-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: allow VM_FAULT_RETRY for multiple timesPeter Xu
The idea comes from a discussion between Linus and Andrea [1]. Before this patch we only allow a page fault to retry once. We achieved this by clearing the FAULT_FLAG_ALLOW_RETRY flag when doing handle_mm_fault() the second time. This was majorly used to avoid unexpected starvation of the system by looping over forever to handle the page fault on a single page. However that should hardly happen, and after all for each code path to return a VM_FAULT_RETRY we'll first wait for a condition (during which time we should possibly yield the cpu) to happen before VM_FAULT_RETRY is really returned. This patch removes the restriction by keeping the FAULT_FLAG_ALLOW_RETRY flag when we receive VM_FAULT_RETRY. It means that the page fault handler now can retry the page fault for multiple times if necessary without the need to generate another page fault event. Meanwhile we still keep the FAULT_FLAG_TRIED flag so page fault handler can still identify whether a page fault is the first attempt or not. Then we'll have these combinations of fault flags (only considering ALLOW_RETRY flag and TRIED flag): - ALLOW_RETRY and !TRIED: this means the page fault allows to retry, and this is the first try - ALLOW_RETRY and TRIED: this means the page fault allows to retry, and this is not the first try - !ALLOW_RETRY and !TRIED: this means the page fault does not allow to retry at all - !ALLOW_RETRY and TRIED: this is forbidden and should never be used In existing code we have multiple places that has taken special care of the first condition above by checking against (fault_flags & FAULT_FLAG_ALLOW_RETRY). This patch introduces a simple helper to detect the first retry of a page fault by checking against both (fault_flags & FAULT_FLAG_ALLOW_RETRY) and !(fault_flag & FAULT_FLAG_TRIED) because now even the 2nd try will have the ALLOW_RETRY set, then use that helper in all existing special paths. One example is in __lock_page_or_retry(), now we'll drop the mmap_sem only in the first attempt of page fault and we'll keep it in follow up retries, so old locking behavior will be retained. This will be a nice enhancement for current code [2] at the same time a supporting material for the future userfaultfd-writeprotect work, since in that work there will always be an explicit userfault writeprotect retry for protected pages, and if that cannot resolve the page fault (e.g., when userfaultfd-writeprotect is used in conjunction with swapped pages) then we'll possibly need a 3rd retry of the page fault. It might also benefit other potential users who will have similar requirement like userfault write-protection. GUP code is not touched yet and will be covered in follow up patch. Please read the thread below for more information. [1] https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/ [2] https://lore.kernel.org/lkml/20181230154648.GB9832@redhat.com/ Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220160246.9790-1-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: fix __get_user_pages() on fault retry of hugetlbPeter Xu
When follow_hugetlb_page() returns with *locked==0, it means we've got a VM_FAULT_RETRY within the fauling process and we've released the mmap_sem. When that happens, we should stop and bail out. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-3-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: rename "nonblocking" to "locked" where properPeter Xu
Patch series "mm: Page fault enhancements", v6. This series contains cleanups and enhancements to current page fault logic. The whole idea comes from the discussion between Andrea and Linus on the bug reported by syzbot here: https://lkml.org/lkml/2017/11/2/833 Basically it does two things: (a) Allows the page fault logic to be more interactive on not only SIGKILL, but also the rest of userspace signals, and, (b) Allows the page fault retry (VM_FAULT_RETRY) to happen for more than once. For (a): with the changes we should be able to react faster when page faults are working in parallel with userspace signals like SIGSTOP and SIGCONT (and more), and with that we can remove the buggy part in userfaultfd and benefit the whole page fault mechanism on faster signal processing to reach the userspace. For (b), we should be able to allow the page fault handler to loop for even more than twice. Some context: for now since we have FAULT_FLAG_ALLOW_RETRY we can allow to retry the page fault once with the same interrupt context, however never more than twice. This can be not only a potential cleanup to remove this assumption since AFAIU the code itself doesn't really have this twice-only limitation (though that should be a protective approach in the past), at the same time it'll greatly simplify future works like userfaultfd write-protect where it's possible to retry for more than twice (please have a look at [1] below for a possible user that might require the page fault to be handled for a third time; if we can remove the retry limitation we can simply drop that patch and those complexity). This patch (of 16): There's plenty of places around __get_user_pages() that has a parameter "nonblocking" which does not really mean that "it won't block" (because it can really block) but instead it shows whether the mmap_sem is released by up_read() during the page fault handling mostly when VM_FAULT_RETRY is returned. We have the correct naming in e.g. get_user_pages_locked() or get_user_pages_remote() as "locked", however there're still many places that are using the "nonblocking" as name. Renaming the places to "locked" where proper to better suite the functionality of the variable. While at it, fixing up some of the comments accordingly. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Cracauer <cracauer@cons.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/vma: make is_vma_temporary_stack() available for general useAnshuman Khandual
Currently the declaration and definition for is_vma_temporary_stack() are scattered. Lets make is_vma_temporary_stack() helper available for general use and also drop the declaration from (include/linux/huge_mm.h) which is no longer required. While at this, rename this as vma_is_temporary_stack() in line with existing helpers. This should not cause any functional change. Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1582782965-3274-4-git-send-email-anshuman.khandual@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>