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authorShijie Hu <hushijie3@huawei.com>2020-06-03 16:03:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-03 20:09:49 -0700
commit885902531586d5a20a74099c1357bfdc982befe3 (patch)
tree5035b431fd9fde559d11b9d19508a2a866c011d6 /fs/hugetlbfs
parent4360dfa99ff58edad778bdd07819ee32bbf495b8 (diff)
hugetlbfs: get unmapped area below TASK_UNMAPPED_BASE for hugetlbfs
In a 32-bit program, running on arm64 architecture. When the address space below mmap base is completely exhausted, shmat() for huge pages will return ENOMEM, but shmat() for normal pages can still success on no-legacy mode. This seems not fair. For normal pages, the calling trace of get_unmapped_area() is: => mm->get_unmapped_area() if on legacy mode, => arch_get_unmapped_area() => vm_unmapped_area() if on no-legacy mode, => arch_get_unmapped_area_topdown() => vm_unmapped_area() For huge pages, the calling trace of get_unmapped_area() is: => file->f_op->get_unmapped_area() => hugetlb_get_unmapped_area() => vm_unmapped_area() To solve this issue, we only need to make hugetlb_get_unmapped_area() take the same way as mm->get_unmapped_area(). Add *bottomup() and *topdown() for hugetlbfs, and check current mm->get_unmapped_area() to decide which one to use. If mm->get_unmapped_area is equal to arch_get_unmapped_area_topdown(), hugetlb_get_unmapped_area() calls topdown routine, otherwise calls bottomup routine. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Shijie Hu <hushijie3@huawei.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Will Deacon <will@kernel.org> Cc: Xiaoming Ni <nixiaoming@huawei.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: yangerkun <yangerkun@huawei.com> Cc: ChenGang <cg.chen@huawei.com> Cc: Chen Jie <chenjie6@huawei.com> Link: http://lkml.kernel.org/r/20200518065338.113664-1-hushijie3@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/hugetlbfs')
-rw-r--r--fs/hugetlbfs/inode.c67
1 files changed, 59 insertions, 8 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 991c60c7ffe0..f3420a643b4f 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -38,6 +38,7 @@
#include <linux/uio.h>
#include <linux/uaccess.h>
+#include <linux/sched/mm.h>
static const struct super_operations hugetlbfs_ops;
static const struct address_space_operations hugetlbfs_aops;
@@ -191,13 +192,60 @@ out:
#ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
static unsigned long
+hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct hstate *h = hstate_file(file);
+ struct vm_unmapped_area_info info;
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = current->mm->mmap_base;
+ info.high_limit = TASK_SIZE;
+ info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+ info.align_offset = 0;
+ return vm_unmapped_area(&info);
+}
+
+static unsigned long
+hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct hstate *h = hstate_file(file);
+ struct vm_unmapped_area_info info;
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+ info.high_limit = current->mm->mmap_base;
+ info.align_mask = PAGE_MASK & ~huge_page_mask(h);
+ info.align_offset = 0;
+ addr = vm_unmapped_area(&info);
+
+ /*
+ * A failed mmap() very likely causes application failure,
+ * so fall back to the bottom-up function here. This scenario
+ * can happen with large stack limits and large mmap()
+ * allocations.
+ */
+ if (unlikely(offset_in_page(addr))) {
+ VM_BUG_ON(addr != -ENOMEM);
+ info.flags = 0;
+ info.low_limit = current->mm->mmap_base;
+ info.high_limit = TASK_SIZE;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+
+static unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct hstate *h = hstate_file(file);
- struct vm_unmapped_area_info info;
if (len & ~huge_page_mask(h))
return -EINVAL;
@@ -218,13 +266,16 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
return addr;
}
- info.flags = 0;
- info.length = len;
- info.low_limit = TASK_UNMAPPED_BASE;
- info.high_limit = TASK_SIZE;
- info.align_mask = PAGE_MASK & ~huge_page_mask(h);
- info.align_offset = 0;
- return vm_unmapped_area(&info);
+ /*
+ * Use mm->get_unmapped_area value as a hint to use topdown routine.
+ * If architectures have special needs, they should define their own
+ * version of hugetlb_get_unmapped_area.
+ */
+ if (mm->get_unmapped_area == arch_get_unmapped_area_topdown)
+ return hugetlb_get_unmapped_area_topdown(file, addr, len,
+ pgoff, flags);
+ return hugetlb_get_unmapped_area_bottomup(file, addr, len,
+ pgoff, flags);
}
#endif