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* mm/hugetlb: remove unused arch hook prepare/release_hugepageDominik Dingel2015-06-251-10/+0
| | | | | | | | | | | | With s390 dropping support for emulated hugepages, the last user of arch_prepare_hugepage and arch_release_hugepage is gone. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: handle races in alloc_huge_page and hugetlb_reserve_pagesMike Kravetz2015-06-241-4/+35
| | | | | | | | | | | | | | | | | | | | | alloc_huge_page and hugetlb_reserve_pages use region_chg to calculate the number of pages which will be added to the reserve map. Subpool and global reserve counts are adjusted based on the output of region_chg. Before the pages are actually added to the reserve map, these routines could race and add fewer pages than expected. If this happens, the subpool and global reserve counts are not correct. Compare the number of pages actually added (region_add) to those expected to added (region_chg). If fewer pages are actually added, this indicates a race and adjust counters accordingly. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: compute/return the number of regions added by region_add()Mike Kravetz2015-06-241-24/+48
| | | | | | | | | | | | | | | | | | | | Modify region_add() to keep track of regions(pages) added to the reserve map and return this value. The return value can be compared to the return value of region_chg() to determine if the map was modified between calls. Make vma_commit_reservation() also pass along the return value of region_add(). In the normal case, we want vma_commit_reservation to return the same value as the preceding call to vma_needs_reservation. Create a common __vma_reservation_common routine to help keep the special case return values in sync Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: document the reserve map/region tracking routinesMike Kravetz2015-06-241-2/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While working on hugetlbfs fallocate support, I noticed the following race in the existing code. It is unlikely that this race is hit very often in the current code. However, if more functionality to add and remove pages to hugetlbfs mappings (such as fallocate) is added the likelihood of hitting this race will increase. alloc_huge_page and hugetlb_reserve_pages use information from the reserve map to determine if there are enough available huge pages to complete the operation, as well as adjust global reserve and subpool usage counts. The order of operations is as follows: - call region_chg() to determine the expected change based on reserve map - determine if enough resources are available for this operation - adjust global counts based on the expected change - call region_add() to update the reserve map The issue is that reserve map could change between the call to region_chg and region_add. In this case, the counters which were adjusted based on the output of region_chg will not be correct. In order to hit this race today, there must be an existing shared hugetlb mmap created with the MAP_NORESERVE flag. A page fault to allocate a huge page via this mapping must occur at the same another task is mapping the same region without the MAP_NORESERVE flag. The patch set does not prevent the race from happening. Rather, it adds simple functionality to detect when the race has occurred. If a race is detected, then the incorrect counts are adjusted. Review comments pointed out the need for documentation of the existing region/reserve map routines. This patch set also adds documentation in this area. This patch (of 3): This is a documentation only patch and does not modify any code. Descriptions of the routines used for reserve map/region tracking are added. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: introduce minimum hugepage orderNaoya Horiguchi2015-06-241-8/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently the initial value of order in dissolve_free_huge_page is 64 or 32, which leads to the following warning in static checker: mm/hugetlb.c:1203 dissolve_free_huge_pages() warn: potential right shift more than type allows '9,18,64' This is a potential risk of infinite loop, because 1 << order (== 0) is used in for-loop like this: for (pfn =3D start_pfn; pfn < end_pfn; pfn +=3D 1 << order) ... So this patch fixes it by using global minimum_order calculated at boot time. text data bss dec hex filename 28313 469 84236 113018 1b97a mm/hugetlb.o 28256 473 84236 112965 1b945 mm/hugetlb.o (patched) Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: reduce arch dependent code about huge_pmd_unshareZhang Zhen2015-06-241-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | Currently we have many duplicates in definitions of huge_pmd_unshare. In all architectures this function just returns 0 when CONFIG_ARCH_WANT_HUGE_PMD_SHARE is N. This patch puts the default implementation in mm/hugetlb.c and lets these architectures use the common code. Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: David Rientjes <rientjes@google.com> Cc: James Yang <James.Yang@freescale.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: cleanup using paeg_huge_active()Naoya Horiguchi2015-04-151-37/+5
| | | | | | | | | | | | | | | Now we have an easy access to hugepages' activeness, so existing helpers to get the information can be cleaned up. [akpm@linux-foundation.org: s/PageHugeActive/page_huge_active/] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: introduce page_huge_activeNaoya Horiguchi2015-04-151-3/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are not safe from calling isolate_huge_page() on a hugepage concurrently, which can make the victim hugepage in invalid state and results in BUG_ON(). The root problem of this is that we don't have any information on struct page (so easily accessible) about hugepages' activeness. Note that hugepages' activeness means just being linked to hstate->hugepage_activelist, which is not the same as normal pages' activeness represented by PageActive flag. Normal pages are isolated by isolate_lru_page() which prechecks PageLRU before isolation, so let's do similarly for hugetlb with a new paeg_huge_active(). set/clear_page_huge_active() should be called within hugetlb_lock. But hugetlb_cow() and hugetlb_no_page() don't do this, being justified because in these functions set_page_huge_active() is called right after the hugepage is allocated and no other thread tries to isolate it. [akpm@linux-foundation.org: s/PageHugeActive/page_huge_active/, make it return bool] [fengguang.wu@intel.com: set_page_huge_active() can be static] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlbfs: accept subpool min_size mount option and setup accordinglyMike Kravetz2015-04-151-4/+21
| | | | | | | | | | | | | | | | | | | Make 'min_size=<value>' be an option when mounting a hugetlbfs. This option takes the same value as the 'size' option. min_size can be specified without specifying size. If both are specified, min_size must be less that or equal to size else the mount will fail. If min_size is specified, then at mount time an attempt is made to reserve min_size pages. If the reservation fails, the mount fails. At umount time, the reserved pages are released. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlbfs: add minimum size accounting to subpoolsMike Kravetz2015-04-151-23/+100
| | | | | | | | | | | | | | | | | | | The same routines that perform subpool maximum size accounting hugepage_subpool_get/put_pages() are modified to also perform minimum size accounting. When a delta value is passed to these routines, calculate how global reservations must be adjusted to maintain the subpool minimum size. The routines now return this global reserve count adjustment. This global reserve count adjustment is then passed to the global accounting routine hugetlb_acct_memory(). Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlbfs: add minimum size tracking fields to subpool structureMike Kravetz2015-04-151-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | hugetlbfs allocates huge pages from the global pool as needed. Even if the global pool contains a sufficient number pages for the filesystem size at mount time, those global pages could be grabbed for some other use. As a result, filesystem huge page allocations may fail due to lack of pages. Applications such as a database want to use huge pages for performance reasons. hugetlbfs filesystem semantics with ownership and modes work well to manage access to a pool of huge pages. However, the application would like some reasonable assurance that allocations will not fail due to a lack of huge pages. At application startup time, the application would like to configure itself to use a specific number of huge pages. Before starting, the application can check to make sure that enough huge pages exist in the system global pools. However, there are no guarantees that those pages will be available when needed by the application. What the application wants is exclusive use of a subset of huge pages. Add a new hugetlbfs mount option 'min_size=<value>' to indicate that the specified number of pages will be available for use by the filesystem. At mount time, this number of huge pages will be reserved for exclusive use of the filesystem. If there is not a sufficient number of free pages, the mount will fail. As pages are allocated to and freeed from the filesystem, the number of reserved pages is adjusted so that the specified minimum is maintained. This patch (of 4): Add a field to the subpool structure to indicate the minimimum number of huge pages to always be used by this subpool. This minimum count includes allocated pages as well as reserved pages. If the minimum number of pages for the subpool have not been allocated, pages are reserved up to this minimum. An additional field (rsv_hpages) is used to track the number of pages reserved to meet this minimum size. The hstate pointer in the subpool is convenient to have when reserving and unreserving the pages. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb: abort __get_user_pages if current has been oom killedDavid Rientjes2015-04-141-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | If __get_user_pages() is faulting a significant number of hugetlb pages, usually as the result of mmap(MAP_LOCKED), it can potentially allocate a very large amount of memory. If the process has been oom killed, this will cause a lot of memory to potentially deplete memory reserves. In the same way that commit 4779280d1ea4 ("mm: make get_user_pages() interruptible") aborted for pending SIGKILLs when faulting non-hugetlb memory, based on the premise of commit 462e00cc7151 ("oom: stop allocating user memory if TIF_MEMDIE is set"), hugetlb page faults now terminate when the process has been oom killed. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Greg Thelen <gthelen@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: use pmd_page() in follow_huge_pmd()Gerald Schaefer2015-04-141-2/+1
| | | | | | | | | | | | | | | | | | | | | Commit 61f77eda9bbf ("mm/hugetlb: reduce arch dependent code around follow_huge_*") broke follow_huge_pmd() on s390, where pmd and pte layout differ and using pte_page() on a huge pmd will return wrong results. Using pmd_page() instead fixes this. All architectures that were touched by that commit have pmd_page() defined, so this should not break anything on other architectures. Fixes: 61f77eda "mm/hugetlb: reduce arch dependent code around follow_huge_*" Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.cz>, Andrea Arcangeli <aarcange@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb: close race when setting PageTail for gigantic pagesDavid Rientjes2015-03-121-1/+3
| | | | | | | | | | | | | | | | Now that gigantic pages are dynamically allocatable, care must be taken to ensure that p->first_page is valid before setting PageTail. If this isn't done, then it is possible to race and have compound_head() return NULL. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: account pmd page tables to the processKirill A. Shutemov2015-02-111-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: add migration entry check in __unmap_hugepage_rangeNaoya Horiguchi2015-02-111-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | If __unmap_hugepage_range() tries to unmap the address range over which hugepage migration is on the way, we get the wrong page because pte_page() doesn't work for migration entries. This patch simply clears the pte for migration entries as we do for hwpoison entries. Fixes: 290408d4a2 ("hugetlb: hugepage migration core") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [2.6.36+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protectionNaoya Horiguchi2015-02-111-1/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a race condition between hugepage migration and change_protection(), where hugetlb_change_protection() doesn't care about migration entries and wrongly overwrites them. That causes unexpected results like kernel crash. HWPoison entries also can cause the same problem. This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this function to do proper actions. Fixes: 290408d4a2 ("hugetlb: hugepage migration core") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [2.6.36+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: fix getting refcount 0 page in hugetlb_fault()Naoya Horiguchi2015-02-111-16/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When running the test which causes the race as shown in the previous patch, we can hit the BUG "get_page() on refcount 0 page" in hugetlb_fault(). This race happens when pte turns into migration entry just after the first check of is_hugetlb_entry_migration() in hugetlb_fault() passed with false. To fix this, we need to check pte_present() again after huge_ptep_get(). This patch also reorders taking ptl and doing pte_page(), because pte_page() should be done in ptl. Due to this reordering, we need use trylock_page() in page != pagecache_page case to respect locking order. Fixes: 66aebce747ea ("hugetlb: fix race condition in hugetlb_fault()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.2+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: take page table lock in follow_huge_pmd()Naoya Horiguchi2015-02-111-14/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have a race condition between move_pages() and freeing hugepages, where move_pages() calls follow_page(FOLL_GET) for hugepages internally and tries to get its refcount without preventing concurrent freeing. This race crashes the kernel, so this patch fixes it by moving FOLL_GET code for hugepages into follow_huge_pmd() with taking the page table lock. This patch intentionally removes page==NULL check after pte_page. This is justified because pte_page() never returns NULL for any architectures or configurations. This patch changes the behavior of follow_huge_pmd() for tail pages and then tail pages can be pinned/returned. So the caller must be changed to properly handle the returned tail pages. We could have a choice to add the similar locking to follow_huge_(addr|pud) for consistency, but it's not necessary because currently these functions don't support FOLL_GET flag, so let's leave it for future development. Here is the reproducer: $ cat movepages.c #include <stdio.h> #include <stdlib.h> #include <numaif.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 #define PS 0x1000 int main(int argc, char *argv[]) { int i; int nr_hp = strtol(argv[1], NULL, 0); int nr_p = nr_hp * HPS / PS; int ret; void **addrs; int *status; int *nodes; pid_t pid; pid = strtol(argv[2], NULL, 0); addrs = malloc(sizeof(char *) * nr_p + 1); status = malloc(sizeof(char *) * nr_p + 1); nodes = malloc(sizeof(char *) * nr_p + 1); while (1) { for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 1; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); for (i = 0; i < nr_p; i++) { addrs[i] = (void *)ADDR_INPUT + i * PS; nodes[i] = 0; status[i] = 0; } ret = numa_move_pages(pid, nr_p, addrs, nodes, status, MPOL_MF_MOVE_ALL); if (ret == -1) err("move_pages"); } return 0; } $ cat hugepage.c #include <stdio.h> #include <sys/mman.h> #include <string.h> #define ADDR_INPUT 0x700000000000UL #define HPS 0x200000 int main(int argc, char *argv[]) { int nr_hp = strtol(argv[1], NULL, 0); char *p; while (1) { p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0); if (p != (void *)ADDR_INPUT) { perror("mmap"); break; } memset(p, 0, nr_hp * HPS); munmap(p, nr_hp * HPS); } } $ sysctl vm.nr_hugepages=40 $ ./hugepage 10 & $ ./movepages 10 $(pgrep -f hugepage) Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: pmd_huge() returns true for non-present hugepageNaoya Horiguchi2015-02-111-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Migrating hugepages and hwpoisoned hugepages are considered as non-present hugepages, and they are referenced via migration entries and hwpoison entries in their page table slots. This behavior causes race condition because pmd_huge() doesn't tell non-huge pages from migrating/hwpoisoned hugepages. follow_page_mask() is one example where the kernel would call follow_page_pte() for such hugepage while this function is supposed to handle only normal pages. To avoid this, this patch makes pmd_huge() return true when pmd_none() is true *and* pmd_present() is false. We don't have to worry about mixing up non-present pmd entry with normal pmd (pointing to leaf level pte entry) because pmd_present() is true in normal pmd. The same race condition could happen in (x86-specific) gup_pmd_range(), where this patch simply adds pmd_present() check instead of pmd_huge(). This is because gup_pmd_range() is fast path. If we have non-present hugepage in this function, we will go into gup_huge_pmd(), then return 0 at flag mask check, and finally fall back to the slow path. Fixes: 290408d4a2 ("hugetlb: hugepage migration core") Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: <stable@vger.kernel.org> [2.6.36+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb: reduce arch dependent code around follow_huge_*Naoya Horiguchi2015-02-111-15/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently we have many duplicates in definitions around follow_huge_addr(), follow_huge_pmd(), and follow_huge_pud(), so this patch tries to remove the m. The basic idea is to put the default implementation for these functions in mm/hugetlb.c as weak symbols (regardless of CONFIG_ARCH_WANT_GENERAL_HUGETL B), and to implement arch-specific code only when the arch needs it. For follow_huge_addr(), only powerpc and ia64 have their own implementation, and in all other architectures this function just returns ERR_PTR(-EINVAL). So this patch sets returning ERR_PTR(-EINVAL) as default. As for follow_huge_(pmd|pud)(), if (pmd|pud)_huge() is implemented to always return 0 in your architecture (like in ia64 or sparc,) it's never called (the callsite is optimized away) no matter how implemented it is. So in such architectures, we don't need arch-specific implementation. In some architecture (like mips, s390 and tile,) their current arch-specific follow_huge_(pmd|pud)() are effectively identical with the common code, so this patch lets these architecture use the common code. One exception is metag, where pmd_huge() could return non-zero but it expects follow_huge_pmd() to always return NULL. This means that we need arch-specific implementation which returns NULL. This behavior looks strange to me (because non-zero pmd_huge() implies that the architecture supports PMD-based hugepage, so follow_huge_pmd() can/should return some relevant value,) but that's beyond this cleanup patch, so let's keep it. Justification of non-trivial changes: - in s390, follow_huge_pmd() checks !MACHINE_HAS_HPAGE at first, and this patch removes the check. This is OK because we can assume MACHINE_HAS_HPAGE is true when follow_huge_pmd() can be called (note that pmd_huge() has the same check and always returns 0 for !MACHINE_HAS_HPAGE.) - in s390 and mips, we use HPAGE_MASK instead of PMD_MASK as done in common code. This patch forces these archs use PMD_MASK, but it's OK because they are identical in both archs. In s390, both of HPAGE_SHIFT and PMD_SHIFT are 20. In mips, HPAGE_SHIFT is defined as (PAGE_SHIFT + PAGE_SHIFT - 3) and PMD_SHIFT is define as (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3), but PTE_ORDER is always 0, so these are identical. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Steve Capper <steve.capper@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: fix type of hugetlb_treat_as_movable variableAndrey Ryabinin2015-02-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | hugetlb_treat_as_movable declared as unsigned long, but proc_dointvec() used for parsing it: static struct ctl_table vm_table[] = { ... { .procname = "hugepages_treat_as_movable", .data = &hugepages_treat_as_movable, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec, }, This seems harmless, but it's better to use int type here. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Manfred Spraul <manfred@colorfullife.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linuxLinus Torvalds2014-12-151-1/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull drm updates from Dave Airlie: "Highlights: - AMD KFD driver merge This is the AMD HSA interface for exposing a lowlevel interface for GPGPU use. They have an open source userspace built on top of this interface, and the code looks as good as it was going to get out of tree. - Initial atomic modesetting work The need for an atomic modesetting interface to allow userspace to try and send a complete set of modesetting state to the driver has arisen, and been suffering from neglect this past year. No more, the start of the common code and changes for msm driver to use it are in this tree. Ongoing work to get the userspace ioctl finished and the code clean will probably wait until next kernel. - DisplayID 1.3 and tiled monitor exposed to userspace. Tiled monitor property is now exposed for userspace to make use of. - Rockchip drm driver merged. - imx gpu driver moved out of staging Other stuff: - core: panel - MIPI DSI + new panels. expose suggested x/y properties for virtual GPUs - i915: Initial Skylake (SKL) support gen3/4 reset work start of dri1/ums removal infoframe tracking fixes for lots of things. - nouveau: tegra k1 voltage support GM204 modesetting support GT21x memory reclocking work - radeon: CI dpm fixes GPUVM improvements Initial DPM fan control - rcar-du: HDMI support added removed some support for old boards slave encoder driver for Analog Devices adv7511 - exynos: Exynos4415 SoC support - msm: a4xx gpu support atomic helper conversion - tegra: iommu support universal plane support ganged-mode DSI support - sti: HDMI i2c improvements - vmwgfx: some late fixes. - qxl: use suggested x/y properties" * 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits) drm: sti: fix module compilation issue drm/i915: save/restore GMBUS freq across suspend/resume on gen4 drm: sti: correctly cleanup CRTC and planes drm: sti: add HQVDP plane drm: sti: add cursor plane drm: sti: enable auxiliary CRTC drm: sti: fix delay in VTG programming drm: sti: prepare sti_tvout to support auxiliary crtc drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off} drm: sti: fix hdmi avi infoframe drm: sti: remove event lock while disabling vblank drm: sti: simplify gdp code drm: sti: clear all mixer control drm: sti: remove gpio for HDMI hot plug detection drm: sti: allow to change hdmi ddc i2c adapter drm/doc: Document drm_add_modes_noedid() usage drm/i915: Remove '& 0xffff' from the mask given to WA_REG() drm/i915: Invert the mask and val arguments in wa_add() and WA_REG() drm: Zero out DRM object memory upon cleanup drm/i915/bdw: Fix the write setting up the WIZ hashing mode ...
| * mmu_notifier: call mmu_notifier_invalidate_range() from VMMJoerg Roedel2014-11-131-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add calls to the new mmu_notifier_invalidate_range() function to all places in the VMM that need it. Signed-off-by: Joerg Roedel <jroedel@suse.de> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Jay Cornwall <Jay.Cornwall@amd.com> Cc: Oded Gabbay <Oded.Gabbay@amd.com> Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
* | hugetlb: hugetlb_register_all_nodes(): add __init markerLuiz Capitulino2014-12-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This function is only called during initialization. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | hugetlb: alloc_bootmem_huge_page(): use IS_ALIGNED()Luiz Capitulino2014-12-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | No reason to duplicate the code of an existing macro. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: convert i_mmap_mutex to rwsemDavidlohr Bueso2014-12-131-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The i_mmap_mutex is a close cousin of the anon vma lock, both protecting similar data, one for file backed pages and the other for anon memory. To this end, this lock can also be a rwsem. In addition, there are some important opportunities to share the lock when there are no tree modifications. This conversion is straightforward. For now, all users take the write lock. [sfr@canb.auug.org.au: update fremap.c] Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: use new helper functions around the i_mmap_mutexDavidlohr Bueso2014-12-131-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Convert all open coded mutex_lock/unlock calls to the i_mmap_[lock/unlock]_write() helpers. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge branch 'for-3.19' of ↵Linus Torvalds2014-12-111-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup update from Tejun Heo: "cpuset got simplified a bit. cgroup core got a fix on unified hierarchy and grew some effective css related interfaces which will be used for blkio support for writeback IO traffic which is currently being worked on" * 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: implement cgroup_get_e_css() cgroup: add cgroup_subsys->css_e_css_changed() cgroup: add cgroup_subsys->css_released() cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write() cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask() cpuset: lock vs unlock typo cpuset: simplify cpuset_node_allowed API cpuset: convert callback_mutex to a spinlock
| * | cpuset: simplify cpuset_node_allowed APIVladimir Davydov2014-10-271-1/+1
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current cpuset API for checking if a zone/node is allowed to allocate from looks rather awkward. We have hardwall and softwall versions of cpuset_node_allowed with the softwall version doing literally the same as the hardwall version if __GFP_HARDWALL is passed to it in gfp flags. If it isn't, the softwall version may check the given node against the enclosing hardwall cpuset, which it needs to take the callback lock to do. Such a distinction was introduced by commit 02a0e53d8227 ("cpuset: rework cpuset_zone_allowed api"). Before, we had the only version with the __GFP_HARDWALL flag determining its behavior. The purpose of the commit was to avoid sleep-in-atomic bugs when someone would mistakenly call the function without the __GFP_HARDWALL flag for an atomic allocation. The suffixes introduced were intended to make the callers think before using the function. However, since the callback lock was converted from mutex to spinlock by the previous patch, the softwall check function cannot sleep, and these precautions are no longer necessary. So let's simplify the API back to the single check. Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* / mm: hugetlb: fix __unmap_hugepage_range()Hillf Danton2014-12-101-1/+3
|/ | | | | | | | | | | First, after flushing TLB, we have no need to scan pte from start again. Second, before bail out loop, the address is forwarded one step. Signed-off-by: Hillf Danton <hillf.zj@alibaba-inc.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMASasha Levin2014-10-091-7/+7
| | | | | | | | | | | | | | | | | | | | Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract more information when they trigger. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix potential infinite loop in dissolve_free_huge_pages()Li Zhong2014-08-061-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | It is possible for some platforms, such as powerpc to set HPAGE_SHIFT to 0 to indicate huge pages not supported. When this is the case, hugetlbfs could be disabled during boot time: hugetlbfs: disabling because there are no supported hugepage sizes Then in dissolve_free_huge_pages(), order is kept maximum (64 for 64bits), and the for loop below won't end: for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) As suggested by Naoya, below fix checks hugepages_supported() before calling dissolve_free_huge_pages(). [rientjes@google.com: no legitimate reason to call dissolve_free_huge_pages() when !hugepages_supported()] Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb: remove hugetlb_zero and hugetlb_infinityDavid Rientjes2014-08-061-1/+0
| | | | | | | | | | | | | They are unnecessary: "zero" can be used in place of "hugetlb_zero" and passing extra2 == NULL is equivalent to infinity. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb: generalize writes to nr_hugepagesDavid Rientjes2014-08-061-32/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Three different interfaces alter the maximum number of hugepages for an hstate: - /proc/sys/vm/nr_hugepages for global number of hugepages of the default hstate, - /sys/kernel/mm/hugepages/hugepages-X/nr_hugepages for global number of hugepages for a specific hstate, and - /sys/kernel/mm/hugepages/hugepages-X/nr_hugepages/mempolicy for number of hugepages for a specific hstate over the set of allowed nodes. Generalize the code so that a single function handles all of these writes instead of duplicating the code in two different functions. This decreases the number of lines of code, but also reduces the size of .text by about half a percent since set_max_huge_pages() can be inlined. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm,hugetlb: simplify error handling in hugetlb_cow()Davidlohr Bueso2014-08-061-19/+16
| | | | | | | | | | | | | | | | | | | | | When returning from hugetlb_cow(), we always (1) put back the refcount for each referenced page -- always 'old', and 'new' if allocation was successful. And (2) retake the page table lock right before returning, as the callers expects. This logic can be simplified and encapsulated, as proposed in this patch. In addition to cleaner code, we also shave a few bytes off the instruction text: text data bss dec hex filename 28399 462 41328 70189 1122d mm/hugetlb.o-baseline 28367 462 41328 70157 1120d mm/hugetlb.o-patched Passes libhugetlbfs testcases. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm,hugetlb: make unmap_ref_private() return voidDavidlohr Bueso2014-08-061-18/+14
| | | | | | | | | | | | | | This function always returns 1, thus no need to check return value in hugetlb_cow(). By doing so, we can get rid of the unnecessary WARN_ON call. While this logic perhaps existed as a way of identifying future unmap_ref_private() mishandling, reality is it serves no apparent purpose. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kexec: export free_huge_page to VMCOREINFOAtsushi Kumagai2014-07-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PG_head_mask was added into VMCOREINFO to filter huge pages in b3acc56bfe1 ("kexec: save PG_head_mask in VMCOREINFO"), but makedumpfile still need another symbol to filter *hugetlbfs* pages. If a user hope to filter user pages, makedumpfile tries to exclude them by checking the condition whether the page is anonymous, but hugetlbfs pages aren't anonymous while they also be user pages. We know it's possible to detect them in the same way as PageHuge(), so we need the start address of free_huge_page(): int PageHuge(struct page *page) { if (!PageCompound(page)) return 0; page = compound_head(page); return get_compound_page_dtor(page) == free_huge_page; } For that reason, this patch changes free_huge_page() into public to export it to VMCOREINFO. Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> Acked-by: Baoquan He <bhe@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: fix copy_hugetlb_page_range()Naoya Horiguchi2014-07-231-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4a705fef9862 ("hugetlb: fix copy_hugetlb_page_range() to handle migration/hwpoisoned entry") changed the order of huge_ptep_set_wrprotect() and huge_ptep_get(), which leads to breakage in some workloads like hugepage-backed heap allocation via libhugetlbfs. This patch fixes it. The test program for the problem is shown below: $ cat heap.c #include <unistd.h> #include <stdlib.h> #include <string.h> #define HPS 0x200000 int main() { int i; char *p = malloc(HPS); memset(p, '1', HPS); for (i = 0; i < 5; i++) { if (!fork()) { memset(p, '2', HPS); p = malloc(HPS); memset(p, '3', HPS); free(p); return 0; } } sleep(1); free(p); return 0; } $ export HUGETLB_MORECORE=yes ; export HUGETLB_NO_PREFAULT= ; hugectl --heap ./heap Fixes 4a705fef9862 ("hugetlb: fix copy_hugetlb_page_range() to handle migration/hwpoisoned entry"), so is applicable to -stable kernels which include it. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Guillaume Morin <guillaume@morinfr.org> Suggested-by: Guillaume Morin <guillaume@morinfr.org> Acked-by: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [2.6.37+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: fix copy_hugetlb_page_range() to handle migration/hwpoisoned entryNaoya Horiguchi2014-06-231-28/+43
| | | | | | | | | | | | | | | | There's a race between fork() and hugepage migration, as a result we try to "dereference" a swap entry as a normal pte, causing kernel panic. The cause of the problem is that copy_hugetlb_page_range() can't handle "swap entry" family (migration entry and hwpoisoned entry) so let's fix it. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: <stable@vger.kernel.org> [2.6.37+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: rename hugepage_migration_support() to ..._supported()Naoya Horiguchi2014-06-041-1/+1
| | | | | | | | | | | We already have a function named hugepages_supported(), and the similar name hugepage_migration_support() is a bit unconfortable, so let's rename it hugepage_migration_supported(). Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, hugetlb: move the error handle logic out of normal code pathJianyu Zhan2014-06-041-13/+13
| | | | | | | | | | | | | | alloc_huge_page() now mixes normal code path with error handle logic. This patches move out the error handle logic, to make normal code path more clean and redue code duplicate. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Davidlohr Bueso <davidlohr@hp.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: add support for gigantic page allocation at runtimeLuiz Capitulino2014-06-041-11/+155
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | HugeTLB is limited to allocating hugepages whose size are less than MAX_ORDER order. This is so because HugeTLB allocates hugepages via the buddy allocator. Gigantic pages (that is, pages whose size is greater than MAX_ORDER order) have to be allocated at boottime. However, boottime allocation has at least two serious problems. First, it doesn't support NUMA and second, gigantic pages allocated at boottime can't be freed. This commit solves both issues by adding support for allocating gigantic pages during runtime. It works just like regular sized hugepages, meaning that the interface in sysfs is the same, it supports NUMA, and gigantic pages can be freed. For example, on x86_64 gigantic pages are 1GB big. To allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And to free them all: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages The one problem with gigantic page allocation at runtime is that it can't be serviced by the buddy allocator. To overcome that problem, this commit scans all zones from a node looking for a large enough contiguous region. When one is found, it's allocated by using CMA, that is, we call alloc_contig_range() to do the actual allocation. For example, on x86_64 we scan all zones looking for a 1GB contiguous region. When one is found, it's allocated by alloc_contig_range(). One expected issue with that approach is that such gigantic contiguous regions tend to vanish as runtime goes by. The best way to avoid this for now is to make gigantic page allocations very early during system boot, say from a init script. Other possible optimization include using compaction, which is supported by CMA but is not explicitly used by this commit. It's also important to note the following: 1. Gigantic pages allocated at boottime by the hugepages= command-line option can be freed at runtime just fine 2. This commit adds support for gigantic pages only to x86_64. The reason is that I don't have access to nor experience with other archs. The code is arch indepedent though, so it should be simple to add support to different archs 3. I didn't add support for hugepage overcommit, that is allocating a gigantic page on demand when /proc/sys/vm/nr_overcommit_hugepages > 0. The reason is that I don't think it's reasonable to do the hard and long work required for allocating a gigantic page at fault time. But it should be simple to add this if wanted [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: move helpers up in the fileLuiz Capitulino2014-06-041-73/+73
| | | | | | | | | | | | | | | | | | | | | Next commit will add new code which will want to call for_each_node_mask_to_alloc() macro. Move it, its buddy for_each_node_mask_to_free() and their dependencies up in the file so the new code can use them. This is just code movement, no logic change. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: update_and_free_page(): don't clear PG_reserved bitLuiz Capitulino2014-06-041-2/+2
| | | | | | | | | | | | | | | | | | | | | Hugepages pages never get the PG_reserved bit set, so don't clear it. However, note that if the bit gets mistakenly set free_pages_check() will catch it. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: add hstate_is_gigantic()Luiz Capitulino2014-06-041-14/+14
| | | | | | | | | | | | | | | | Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: prep_compound_gigantic_page(): drop __init markerLuiz Capitulino2014-06-041-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The HugeTLB subsystem uses the buddy allocator to allocate hugepages during runtime. This means that hugepages allocation during runtime is limited to MAX_ORDER order. For archs supporting gigantic pages (that is, page sizes greater than MAX_ORDER), this in turn means that those pages can't be allocated at runtime. HugeTLB supports gigantic page allocation during boottime, via the boot allocator. To this end the kernel provides the command-line options hugepagesz= and hugepages=, which can be used to instruct the kernel to allocate N gigantic pages during boot. For example, x86_64 supports 2M and 1G hugepages, but only 2M hugepages can be allocated and freed at runtime. If one wants to allocate 1G gigantic pages, this has to be done at boot via the hugepagesz= and hugepages= command-line options. Now, gigantic page allocation at boottime has two serious problems: 1. Boottime allocation is not NUMA aware. On a NUMA machine the kernel evenly distributes boottime allocated hugepages among nodes. For example, suppose you have a four-node NUMA machine and want to allocate four 1G gigantic pages at boottime. The kernel will allocate one gigantic page per node. On the other hand, we do have users who want to be able to specify which NUMA node gigantic pages should allocated from. So that they can place virtual machines on a specific NUMA node. 2. Gigantic pages allocated at boottime can't be freed At this point it's important to observe that regular hugepages allocated at runtime don't have those problems. This is so because HugeTLB interface for runtime allocation in sysfs supports NUMA and runtime allocated pages can be freed just fine via the buddy allocator. This series adds support for allocating gigantic pages at runtime. It does so by allocating gigantic pages via CMA instead of the buddy allocator. Releasing gigantic pages is also supported via CMA. As this series builds on top of the existing HugeTLB interface, it makes gigantic page allocation and releasing just like regular sized hugepages. This also means that NUMA support just works. For example, to allocate two 1G gigantic pages on node 1, one can do: # echo 2 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages And, to release all gigantic pages on the same node: # echo 0 > \ /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages Please, refer to patch 5/5 for full technical details. Finally, please note that this series is a follow up for a previous series that tried to extend the command-line options set to be NUMA aware: http://marc.info/?l=linux-mm&m=139593335312191&w=2 During the discussion of that series it was agreed that having runtime allocation support for gigantic pages was a better solution. This patch (of 5): This function is going to be used by non-init code in a future commit. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David Rientjes <rientjes@google.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: ensure hugepage access is denied if hugepages are not supportedNishanth Aravamudan2014-05-061-5/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()Mizuma, Masayoshi2014-04-181-0/+1
| | | | | | | | | | | | | | | | soft lockup in freeing gigantic hugepage fixed in commit 55f67141a892 "mm: hugetlb: fix softlockup when a large number of hugepages are freed." can happen in return_unused_surplus_pages(), so let's fix it. Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: hugetlb: fix softlockup when a large number of hugepages are freed.Mizuma, Masayoshi2014-04-071-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When I decrease the value of nr_hugepage in procfs a lot, softlockup happens. It is because there is no chance of context switch during this process. On the other hand, when I allocate a large number of hugepages, there is some chance of context switch. Hence softlockup doesn't happen during this process. So it's necessary to add the context switch in the freeing process as same as allocating process to avoid softlockup. When I freed 12 TB hugapages with kernel-2.6.32-358.el6, the freeing process occupied a CPU over 150 seconds and following softlockup message appeared twice or more. $ echo 6000000 > /proc/sys/vm/nr_hugepages $ cat /proc/sys/vm/nr_hugepages 6000000 $ grep ^Huge /proc/meminfo HugePages_Total: 6000000 HugePages_Free: 6000000 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB $ echo 0 > /proc/sys/vm/nr_hugepages BUG: soft lockup - CPU#16 stuck for 67s! [sh:12883] ... Pid: 12883, comm: sh Not tainted 2.6.32-358.el6.x86_64 #1 Call Trace: free_pool_huge_page+0xb8/0xd0 set_max_huge_pages+0x128/0x190 hugetlb_sysctl_handler_common+0x113/0x140 hugetlb_sysctl_handler+0x1e/0x20 proc_sys_call_handler+0x97/0xd0 proc_sys_write+0x14/0x20 vfs_write+0xb8/0x1a0 sys_write+0x51/0x90 __audit_syscall_exit+0x265/0x290 system_call_fastpath+0x16/0x1b I have not confirmed this problem with upstream kernels because I am not able to prepare the machine equipped with 12TB memory now. However I confirmed that the amount of decreasing hugepages was directly proportional to the amount of required time. I measured required times on a smaller machine. It showed 130-145 hugepages decreased in a millisecond. Amount of decreasing Required time Decreasing rate hugepages (msec) (pages/msec) ------------------------------------------------------------ 10,000 pages == 20GB 70 - 74 135-142 30,000 pages == 60GB 208 - 229 131-144 It means decrement of 6TB hugepages will trigger softlockup with the default threshold 20sec, in this decreasing rate. Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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