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authorShijie Hu <hushijie3@huawei.com>2020-06-03 16:03:34 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-09 09:03:28 +0200
commit6a79b2433eb1f124c0129450a82e730f6a03bdfe (patch)
tree4ab127dbbfcfa7797c81494b61fd9ca722779d67 /fs/hugetlbfs
parentb69e60f6fc00cedf9effbd44fd2dbdea5c6b91d3 (diff)
hugetlbfs: get unmapped area below TASK_UNMAPPED_BASE for hugetlbfs
commit 885902531586d5a20a74099c1357bfdc982befe3 upstream. 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> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 358398b1fe0c..104061c3f1ba 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;
@@ -201,13 +202,60 @@ 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;
@@ -228,13 +276,16 @@ 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