dm verity fec: fix GFP flags used with mempool_alloc() (34c96507) · Commits · 戴 / test

mempool_alloc() cannot fail for GFP_NOIO allocation, so there is no point testing for failure. One place the code tested for failure was passing "0" as the GFP flags. This is most unusual and is probably meant to be GFP_NOIO, so that is changed. Also, allocation from ->extra_pool and ->prealloc_pool are repeated before releasing the previous allocation. This can deadlock if the code is servicing a write under high memory pressure. To avoid deadlocks, change these to use GFP_NOWAIT and leave the error handling in place. Signed-off-by:

NeilBrown <neilb@suse.com> Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-verity-fec.c

+5 −16

Original line number	Diff line number	Diff line
		@@ -308,19 +308,14 @@ static int fec_alloc_bufs(struct dm_verity v, struct dm_verity_fec_io fio)
		{
		unsigned n;

		if (!fio->rs) {
		fio->rs = mempool_alloc(v->fec->rs_pool, 0);
		if (unlikely(!fio->rs)) {
		DMERR("failed to allocate RS");
		return -ENOMEM;
		}
		}
		if (!fio->rs)
		fio->rs = mempool_alloc(v->fec->rs_pool, GFP_NOIO);

		fec_for_each_prealloc_buffer(n) {
		if (fio->bufs[n])
		continue;

		fio->bufs[n] = mempool_alloc(v->fec->prealloc_pool, GFP_NOIO);
		fio->bufs[n] = mempool_alloc(v->fec->prealloc_pool, GFP_NOWAIT);
		if (unlikely(!fio->bufs[n])) {
		DMERR("failed to allocate FEC buffer");
		return -ENOMEM;
		@@ -332,22 +327,16 @@ static int fec_alloc_bufs(struct dm_verity v, struct dm_verity_fec_io fio)
		if (fio->bufs[n])
		continue;

		fio->bufs[n] = mempool_alloc(v->fec->extra_pool, GFP_NOIO);
		fio->bufs[n] = mempool_alloc(v->fec->extra_pool, GFP_NOWAIT);
		/* we can manage with even one buffer if necessary */
		if (unlikely(!fio->bufs[n]))
		break;
		}
		fio->nbufs = n;

		if (!fio->output) {
		if (!fio->output)
		fio->output = mempool_alloc(v->fec->output_pool, GFP_NOIO);

		if (!fio->output) {
		DMERR("failed to allocate FEC page");
		return -ENOMEM;
		}
		}

		return 0;
		}

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