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authorDaniel Jordan <daniel.m.jordan@oracle.com>2017-08-02 13:31:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-08-02 16:34:46 -0700
commit2be7cfed995e25de1ffaffe14cc065b7ffb528e0 (patch)
treeacd9b18af66852f0b6ee0f3a807e21d0d5b184de /mm/hugetlb.c
parent4d3f5d04d69e9479a3df88ceb0e2cd8188a49366 (diff)
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mm/hugetlb.c: __get_user_pages ignores certain follow_hugetlb_page errors
Commit 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") causes __get_user_pages to ignore certain errors from follow_hugetlb_page. After such error, __get_user_pages subsequently calls faultin_page on the same VMA and start address that follow_hugetlb_page failed on instead of returning the error immediately as it should. In follow_hugetlb_page, when hugetlb_fault returns a value covered under VM_FAULT_ERROR, follow_hugetlb_page returns it without setting nr_pages to 0 as __get_user_pages expects in this case, which causes the following to happen in __get_user_pages: the "while (nr_pages)" check succeeds, we skip the "if (!vma..." check because we got a VMA the last time around, we find no page with follow_page_mask, and we call faultin_page, which calls hugetlb_fault for the second time. This issue also slightly changes how __get_user_pages works. Before, it only returned error if it had made no progress (i = 0). But now, follow_hugetlb_page can clobber "i" with an error code since its new return path doesn't check for progress. So if "i" is nonzero before a failing call to follow_hugetlb_page, that indication of progress is lost and __get_user_pages can return error even if some pages were successfully pinned. To fix this, change follow_hugetlb_page so that it updates nr_pages, allowing __get_user_pages to fail immediately and restoring the "error only if no progress" behavior to __get_user_pages. Tested that __get_user_pages returns when expected on error from hugetlb_fault in follow_hugetlb_page. Fixes: 9a291a7c9428 ("mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified") Link: http://lkml.kernel.org/r/1500406795-58462-1-git-send-email-daniel.m.jordan@oracle.com Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: James Morse <james.morse@arm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: zhong jiang <zhongjiang@huawei.com> Cc: <stable@vger.kernel.org> [4.12.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r--mm/hugetlb.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bc48ee783dd9..a1a0ac0ad6f6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4078,6 +4078,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long vaddr = *position;
unsigned long remainder = *nr_pages;
struct hstate *h = hstate_vma(vma);
+ int err = -EFAULT;
while (vaddr < vma->vm_end && remainder) {
pte_t *pte;
@@ -4154,11 +4155,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
}
ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
if (ret & VM_FAULT_ERROR) {
- int err = vm_fault_to_errno(ret, flags);
-
- if (err)
- return err;
-
+ err = vm_fault_to_errno(ret, flags);
remainder = 0;
break;
}
@@ -4213,7 +4210,7 @@ same_page:
*/
*position = vaddr;
- return i ? i : -EFAULT;
+ return i ? i : err;
}
#ifndef __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE