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  1. 14 3月, 2021 3 次提交
    • P
      mm: use is_cow_mapping() across tree where proper · ca6eb14d
      由 Peter Xu 提交于 
      After is_cow_mapping() is exported in mm.h, replace some manual checks
elsewhere throughout the tree but start to use the new helper.

Link: https://lkml.kernel.org/r/20210217233547.93892-5-peterx@redhat.comSigned-off-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NJason Gunthorpe <jgg@ziepe.ca>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Gal Pressman <galpress@amazon.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Wei Zhang <wzam@amazon.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ca6eb14d
    • P
      hugetlb: break earlier in add_reservation_in_range() when we can · ca7e0457
      由 Peter Xu 提交于 
      All the regions maintained in hugetlb reserved map is inclusive on "from"
but exclusive on "to".  We can break earlier even if rg->from==t because
it already means no possible intersection.

This does not need a Fixes in all cases because when it happens
(rg->from==t) we'll not break out of the loop while we should, however the
next thing we'd do is still add the last file_region we'd need and quit
the loop in the next round.  So this change is not a bugfix (since the old
code should still run okay iiuc), but we'd better still touch it up to
make it logically sane.

Link: https://lkml.kernel.org/r/20210217233547.93892-3-peterx@redhat.comSigned-off-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: NMiaohe Lin <linmiaohe@huawei.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Gal Pressman <galpress@amazon.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Wei Zhang <wzam@amazon.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ca7e0457
    • P
      hugetlb: dedup the code to add a new file_region · 2103cf9c
      由 Peter Xu 提交于 
      Patch series "mm/hugetlb: Early cow on fork, and a few cleanups", v5.

As reported by Gal [1], we still miss the code clip to handle early cow
for hugetlb case, which is true.  Again, it still feels odd to fork()
after using a few huge pages, especially if they're privately mapped to
me..  However I do agree with Gal and Jason in that we should still have
that since that'll complete the early cow on fork effort at least, and
it'll still fix issues where buffers are not well under control and not
easy to apply MADV_DONTFORK.

The first two patches (1-2) are some cleanups I noticed when reading into
the hugetlb reserve map code.  I think it's good to have but they're not
necessary for fixing the fork issue.

The last two patches (3-4) are the real fix.

I tested this with a fork() after some vfio-pci assignment, so I'm pretty
sure the page copy path could trigger well (page will be accounted right
after the fork()), but I didn't do data check since the card I assigned is
some random nic.

  https://github.com/xzpeter/linux/tree/fork-cow-pin-huge

[1] https://lore.kernel.org/lkml/27564187-4a08-f187-5a84-3df50009f6ca@amazon.com/

Introduce hugetlb_resv_map_add() helper to add a new file_region rather
than duplication the similar code twice in add_reservation_in_range().

Link: https://lkml.kernel.org/r/20210217233547.93892-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20210217233547.93892-2-peterx@redhat.comSigned-off-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: NMiaohe Lin <linmiaohe@huawei.com>
Cc: Gal Pressman <galpress@amazon.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Wei Zhang <wzam@amazon.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jann Horn <jannh@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2103cf9c
  3. 25 2月, 2021 22 次提交
  5. 06 2月, 2021 5 次提交
  7. 30 1月, 2021 2 次提交
  9. 13 1月, 2021 1 次提交
  11. 30 12月, 2020 1 次提交
    • M
      mm/hugetlb: fix deadlock in hugetlb_cow error path · e7dd91c4
      由 Mike Kravetz 提交于 
      syzbot reported the deadlock here [1].  The issue is in hugetlb cow
error handling when there are not enough huge pages for the faulting
task which took the original reservation.  It is possible that other
(child) tasks could have consumed pages associated with the reservation.
In this case, we want the task which took the original reservation to
succeed.  So, we unmap any associated pages in children so that they can
be used by the faulting task that owns the reservation.

The unmapping code needs to hold i_mmap_rwsem in write mode.  However,
due to commit c0d0381a ("hugetlbfs: use i_mmap_rwsem for more pmd
sharing synchronization") we are already holding i_mmap_rwsem in read
mode when hugetlb_cow is called.

Technically, i_mmap_rwsem does not need to be held in read mode for COW
mappings as they can not share pmd's.  Modifying the fault code to not
take i_mmap_rwsem in read mode for COW (and other non-sharable) mappings
is too involved for a stable fix.

Instead, we simply drop the hugetlb_fault_mutex and i_mmap_rwsem before
unmapping.  This is OK as it is technically not needed.  They are
reacquired after unmapping as expected by calling code.  Since this is
done in an uncommon error path, the overhead of dropping and reacquiring
mutexes is acceptable.

While making changes, remove redundant BUG_ON after unmap_ref_private.

[1] https://lkml.kernel.org/r/000000000000b73ccc05b5cf8558@google.com

Link: https://lkml.kernel.org/r/4c5781b8-3b00-761e-c0c7-c5edebb6ec1a@oracle.com
Fixes: c0d0381a ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization")
Signed-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Reported-by: syzbot+5eee4145df3c15e96625@syzkaller.appspotmail.com
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e7dd91c4
  13. 16 12月, 2020 6 次提交