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    SubjectRe: [PATCH 0/4] Sleeping functions in invalid context bug fixes
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    On Fri, 2019-07-19 at 15:32 +0100, Luis Henriques wrote:
    > Hi,
    >
    > I'm sending three "sleeping function called from invalid context" bug
    > fixes that I had on my TODO for a while. All of them are ceph_buffer_put
    > related, and all the fixes follow the same pattern: delay the operation
    > until the ci->i_ceph_lock is released.
    >
    > The first patch simply allows ceph_buffer_put to receive a NULL buffer so
    > that the NULL check doesn't need to be performed in all the other patches.
    > IOW, it's not really required, just convenient.
    >
    > (Note: maybe these patches should all be tagged for stable.)
    >
    > Luis Henriques (4):
    > libceph: allow ceph_buffer_put() to receive a NULL ceph_buffer
    > ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr()
    > ceph: fix buffer free while holding i_ceph_lock in
    > __ceph_build_xattrs_blob()
    > ceph: fix buffer free while holding i_ceph_lock in fill_inode()
    >
    > fs/ceph/caps.c | 5 ++++-
    > fs/ceph/inode.c | 7 ++++---
    > fs/ceph/snap.c | 4 +++-
    > fs/ceph/super.h | 2 +-
    > fs/ceph/xattr.c | 19 ++++++++++++++-----
    > include/linux/ceph/buffer.h | 3 ++-
    > 6 files changed, 28 insertions(+), 12 deletions(-)

    This all looks good to me. I'll plan to merge these into the testing
    branch soon, and tag them for stable.

    PS: On a related note (and more of a question for Ilya)...

    I'm wondering if we get any benefit from having our own ceph_kvmalloc
    routine. Why are we not better off using the stock kvmalloc routine
    instead? Forcing a vmalloc just because we've gone above 32k allocation
    doesn't seem like the right thing to do.

    PPS: I also wonder if we ought to put a might_sleep() in kvfree(). I
    think that kfree generally doesn't, and I wonder how many uses of this
    end up using kfree until memory ends up fragmented.
    --
    Jeff Layton <jlayton@kernel.org>

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