Messages in this thread | | | From | Mark Hemment <> | Date | Mon, 20 Dec 2021 12:16:29 +0000 | Subject | Re: [PATCH 03/18] MM: use ->swap_rw for reads from SWP_FS_OPS swap-space |
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On Thu, 16 Dec 2021 at 23:54, NeilBrown <neilb@suse.de> wrote: > > To submit an async read with ->swap_rw() we need to allocate > a structure to hold the kiocb and other details. swap_readpage() cannot > handle transient failure, so create a mempool to provide the structures. > > Signed-off-by: NeilBrown <neilb@suse.de> > --- > mm/page_io.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++------ > mm/swap.h | 1 + > mm/swapfile.c | 5 +++++ > 3 files changed, 58 insertions(+), 6 deletions(-) ... > diff --git a/mm/swapfile.c b/mm/swapfile.c > index f23d9ff21cf8..43539be38e68 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -2401,6 +2401,11 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) > if (ret < 0) > return ret; > sis->flags |= SWP_ACTIVATED; > + if ((sis->flags & SWP_FS_OPS) && > + sio_pool_init() != 0) { > + destroy_swap_extents(sis); > + return -ENOMEM; > + } > return ret; > }
This code is called before 'swapon_mutex' is taken in the swapon code path, so possible for multiple swapons to race here creating two (or more) memory pools.
Mark
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