Messages in this thread | | | Date | Mon, 30 Jun 2014 17:10:54 -0700 (PDT) | From | Hugh Dickins <> | Subject | Re: [PATCH mmotm/next] mm: memcontrol: rewrite charge API: fix shmem_unuse |
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On Mon, 30 Jun 2014, Andrew Morton wrote: > On Mon, 30 Jun 2014 15:48:39 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote: > > - return 0; > > + return -EAGAIN; > > Maybe it's time to document the shmem_unuse_inode() return values.
Oh dear. I had hoped they would look after themselves. This one is a private matter between shmem_unuse_inode and its one caller, just below.
> > + if (error) { > > + if (error != -ENOMEM) > > + error = 0; > > mem_cgroup_cancel_charge(page, memcg); > > } else > > mem_cgroup_commit_charge(page, memcg, true); > > If I'm reading this correctly, shmem_unuse() can now return -EAGAIN and > that can get all the way back to userspace. `man 2 swapoff' doesn't > know this...
if (error) { if (error != -ENOMEM) error = 0; ... return error;
So the only values returned from shmem_unuse_inode() to its caller try_to_unuse() are 0 and -ENOMEM. Those may get passed back to the user, but -EAGAIN was just an internal shmem.c detail.
Hugh
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