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    SubjectRe: Fw: two 2.6.13-rc3-mm3 oddities
    I am ccing this to linux-kernel for a wider audience.

    On Wed, Aug 03, 2005 at 09:56:44AM +1000, Andrew Morton wrote:
    > Subject: two 2.6.13-rc3-mm3 oddities
    > Just wanted to record a couple of oddities I noticed with 2.6.13-rc3-mm3
    > (maybe there before: I hardly tested -mm1 and didn't even download -mm2),
    > which have gone away in 2.6.13-rc4-mm1 - so of no great importance, but
    > perhaps worth noting in case they resurface later.
    > One time my tmpfs-and-looped-tmpfs-kernel-builds collapsed with lots of
    > VFS: file-max limit 49778 reached
    > messages, which I imagine was a side-effect of the struct file RCU
    > patches you've dropped from -rc4-mm1, perhaps a grace period problem.

    Hugh, could you please try this with the experimental patch below ?
    Manfred, is it safe to decrement nr_files in file_free()
    instead of the destructor ? I can't see any problem.

    > And repeatably (after a couple of hours or so), on both i386 and x86_64,
    > those tests hung waiting on page locks, as if there was a missing
    > unlock_page (or a spurious SetPageLocked) somewhere. I didn't have
    > time to do any bisection, but studying source diffs showed no likely
    > candidates whatsoever (I did wonder about Nick's __ClearPageDirty,
    > but reproduced the problem with that backed out). As I say, gone
    > away (same tests on -rc4-mm1 have run two days), but curious.

    Hugh, can you mail me the exact test you run ? I would like to run
    it myself and see if I can reproduce it.


    nr_files need to decremented before the file structure is handed
    over to RCU.

    Signed-off-by: Dipankar Sarma <>

    fs/file_table.c | 8 ++++----
    1 files changed, 4 insertions(+), 4 deletions(-)

    diff -puN fs/file_table.c~files-fix-nr-files fs/file_table.c
    --- linux-2.6.13-rc3-mm3-fixes/fs/file_table.c~files-fix-nr-files 2005-08-08 18:28:12.000000000 +0530
    +++ linux-2.6.13-rc3-mm3-fixes-dipankar/fs/file_table.c 2005-08-08 18:32:31.000000000 +0530
    @@ -48,10 +48,6 @@ void filp_ctor(void * objp, struct kmem_

    void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
    - unsigned long flags;
    - spin_lock_irqsave(&filp_count_lock, flags);
    - files_stat.nr_files--;
    - spin_unlock_irqrestore(&filp_count_lock, flags);

    static inline void file_free_rcu(struct rcu_head *head)
    @@ -62,6 +58,10 @@ static inline void file_free_rcu(struct

    static inline void file_free(struct file *f)
    + unsigned long flags;
    + spin_lock_irqsave(&filp_count_lock, flags);
    + files_stat.nr_files--;
    + spin_unlock_irqrestore(&filp_count_lock, flags);
    call_rcu(&f->f_rcuhead, file_free_rcu);

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      Last update: 2005-08-08 16:12    [W:0.024 / U:219.352 seconds]
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