[ adding linux-raid ] Apologies for the delay, the recent ping from Kees made me take a closer look. On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@xxxxxxxxxx> wrote: > In the quest to remove VLAs from the kernel[1], this moves the > allocation of coefs and blocks from the stack to being kmalloc()ed. > > [1] https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Kyle Spiers <ksspiers@xxxxxxxxxx> > --- > Forgot to add slab.h > --- > crypto/async_tx/async_pq.c | 18 ++++++++++++++---- > crypto/async_tx/raid6test.c | 9 ++++++++- > 2 files changed, 22 insertions(+), 5 deletions(-) > > diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c > index 56bd612927ab..af1912313a23 100644 > --- a/crypto/async_tx/async_pq.c > +++ b/crypto/async_tx/async_pq.c > @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks, > (src_cnt <= dma_maxpq(device, 0) || > dma_maxpq(device, DMA_PREP_CONTINUE) > 0) && > is_dma_pq_aligned(device, offset, 0, len)) { > - struct dma_async_tx_descriptor *tx; > + struct dma_async_tx_descriptor *tx = NULL; > enum dma_ctrl_flags dma_flags = 0; > - unsigned char coefs[src_cnt]; > + unsigned char *coefs; > int i, j; > > /* run the p+q asynchronously */ > @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks, > * sources and update the coefficients accordingly > */ > unmap->len = len; > + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL); At a minimum this needs to be GFP_NOIO since raid may be in the page-reclaim path. However, I think it may be better to allocate this with the rest of the stripe resources and pass it in as a scratch buffer. See the usage / implementation of scribble_alloc() in drivers/md/raid5.c.
