On Mon, May 19, 2025 at 1:05 PM Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, May 19, 2025 at 11:47:18AM +0530, Bharat Bhushan wrote: > > > > > > + /* Allocate extra memory for SG and response address alignment */ > > > > + total_mem_len = ALIGN(info_len, OTX2_CPT_DPTR_RPTR_ALIGN) + dlen; > > > > This add extra memory for 8-byte (OTX2_CPT_DPTR_RPTR_ALIGN) alignment > > > > > > + total_mem_len = ALIGN(total_mem_len, OTX2_CPT_RES_ADDR_ALIGN) + > > > > + sizeof(union otx2_cpt_res_s); > > > > This add extra memory for 32-byte (OTX2_CPT_RES_ADDR_ALIGN)) > > In case not observed, OTX2_CPT_RES_ADDR_ALIGN is not the same as > > OTX2_CPT_DPTR_RPTR_ALIGN. > > But it doesn't do that. Look, assume that total_mem_len is 64, > then ALIGN(64, 32) will still be 64. You're not adding any extra > space for the alignment padding. > > OTOH, kmalloc can return something that has a page offset of 8, > and you will need 24 extra bytes in your structure to make it > align at 32. > > Now of course if you're very lucky, and total_mem_len starts out > at 8, then it would work but that's purely by chance. Thanks for explaining, will change in the next version. Thanks -Bharat > > Cheers, > -- > Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
