Hi,

On Tue, Nov 27, 2018 at 06:57:32AM +0000, Sasha Levin wrote:

Hi,

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag, fixing commit: 4c27fe4c4c84 userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support.

The bot has tested the following trees: v4.19.4, v4.14.83,

v4.19.4: Build OK! v4.14.83: Failed to apply! Possible dependencies: 2a70f6a76bb8 ("memcg, thp: do not invoke oom killer on thp charges") 2cf855837b89 ("memcontrol: schedule throttling if we are congested")

How should we proceed with this patch?

Below is the same patch backported to 4.14.83. With it the patch 5/5 in the series applies cleanly.

From 89135f0df0323f38c0b036c87688f5a7e3cfa9e9 Mon Sep 17 00:00:00 2001

From: Andrea Arcangeli aarcange@redhat.com Date: Mon, 26 Nov 2018 12:34:51 -0500 Subject: [PATCH v4.14.83] userfaultfd: shmem: add i_size checks

With MAP_SHARED: recheck the i_size after taking the PT lock, to serialize against truncate with the PT lock. Delete the page from the pagecache if the i_size_read check fails.

With MAP_PRIVATE: check the i_size after the PT lock before mapping anonymous memory or zeropages into the MAP_PRIVATE shmem mapping.

A mostly irrelevant cleanup: like we do the delete_from_page_cache() pagecache removal after dropping the PT lock, the PT lock is a spinlock so drop it before the sleepable page lock.

Reviewed-by: Mike Rapoport rppt@linux.ibm.com Reviewed-by: Hugh Dickins hughd@google.com Reported-by: Jann Horn jannh@google.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Cc: stable@vger.kernel.org Signed-off-by: Andrea Arcangeli aarcange@redhat.com Signed-off-by: Mike Rapoport rppt@linux.ibm.com --- mm/shmem.c | 18 ++++++++++++++++-- mm/userfaultfd.c | 26 ++++++++++++++++++++++++-- 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c index 8019118..70b9fb9 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2238,6 +2238,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, struct page *page; pte_t _dst_pte, *dst_pte; int ret; + pgoff_t offset, max_off;

ret = -ENOMEM; if (!shmem_inode_acct_block(inode, 1)) @@ -2275,6 +2276,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, __SetPageSwapBacked(page); __SetPageUptodate(page);

+ ret = -EFAULT; + offset = linear_page_index(dst_vma, dst_addr); + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(offset >= max_off)) + goto out_release; + ret = mem_cgroup_try_charge(page, dst_mm, gfp, &memcg, false); if (ret) goto out_release; @@ -2293,8 +2300,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (dst_vma->vm_flags & VM_WRITE) _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));

- ret = -EEXIST; dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); + + ret = -EFAULT; + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + if (unlikely(offset >= max_off)) + goto out_release_uncharge_unlock; + + ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock;

@@ -2312,13 +2325,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,

/* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); - unlock_page(page); pte_unmap_unlock(dst_pte, ptl); + unlock_page(page); ret = 0; out: return ret; out_release_uncharge_unlock: pte_unmap_unlock(dst_pte, ptl); + delete_from_page_cache(page); out_release_uncharge: mem_cgroup_cancel_charge(page, memcg, false); out_release: diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 5dbfcac0..5d70fdb 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -34,6 +34,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, void *page_kaddr; int ret; struct page *page; + pgoff_t offset, max_off; + struct inode *inode;

if (!*pagep) { ret = -ENOMEM; @@ -74,8 +76,17 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, if (dst_vma->vm_flags & VM_WRITE) _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));

- ret = -EEXIST; dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); + if (dst_vma->vm_file) { + /* the shmem MAP_PRIVATE case requires checking the i_size */ + inode = dst_vma->vm_file->f_inode; + offset = linear_page_index(dst_vma, dst_addr); + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + ret = -EFAULT; + if (unlikely(offset >= max_off)) + goto out_release_uncharge_unlock; + } + ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock;

@@ -109,11 +120,22 @@ static int mfill_zeropage_pte(struct mm_struct *dst_mm, pte_t _dst_pte, *dst_pte; spinlock_t *ptl; int ret; + pgoff_t offset, max_off; + struct inode *inode;

_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), dst_vma->vm_page_prot)); - ret = -EEXIST; dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); + if (dst_vma->vm_file) { + /* the shmem MAP_PRIVATE case requires checking the i_size */ + inode = dst_vma->vm_file->f_inode; + offset = linear_page_index(dst_vma, dst_addr); + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + ret = -EFAULT; + if (unlikely(offset >= max_off)) + goto out_unlock; + } + ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_unlock; set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);