The patch titled Subject: crypto: scompress: remove memcpy if sg_nents is 1 has been added to the -mm mm-unstable branch. Its filename is crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Barry Song <v-songbaohua@xxxxxxxx> Subject: crypto: scompress: remove memcpy if sg_nents is 1 Date: Sat, 17 Feb 2024 17:51:02 +1300 while sg_nents is 1 which is always true for the current kernel as the only user - zswap is the case, we should remove two big memcpy. Link: https://lkml.kernel.org/r/20240217045102.55339-4-21cnbao@xxxxxxxxx Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> Tested-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> Cc: Chris Li <chrisl@xxxxxxxxxx> Cc: Dan Streetman <ddstreet@xxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Nhat Pham <nphamcs@xxxxxxxxx> Cc: Seth Jennings <sjenning@xxxxxxxxxx> Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx> Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- crypto/scompress.c | 36 +++++++++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 7 deletions(-) --- a/crypto/scompress.c~crypto-scompress-remove-memcpy-if-sg_nents-is-1 +++ a/crypto/scompress.c @@ -117,6 +117,7 @@ static int scomp_acomp_comp_decomp(struc struct crypto_scomp *scomp = *tfm_ctx; void **ctx = acomp_request_ctx(req); struct scomp_scratch *scratch; + void *src, *dst; unsigned int dlen; int ret; @@ -134,13 +135,25 @@ static int scomp_acomp_comp_decomp(struc scratch = raw_cpu_ptr(&scomp_scratch); spin_lock(&scratch->lock); - scatterwalk_map_and_copy(scratch->src, req->src, 0, req->slen, 0); + if (sg_nents(req->src) == 1) { + src = kmap_local_page(sg_page(req->src)) + req->src->offset; + } else { + scatterwalk_map_and_copy(scratch->src, req->src, 0, + req->slen, 0); + src = scratch->src; + } + + if (req->dst && sg_nents(req->dst) == 1) + dst = kmap_local_page(sg_page(req->dst)) + req->dst->offset; + else + dst = scratch->dst; + if (dir) - ret = crypto_scomp_compress(scomp, scratch->src, req->slen, - scratch->dst, &req->dlen, *ctx); + ret = crypto_scomp_compress(scomp, src, req->slen, + dst, &req->dlen, *ctx); else - ret = crypto_scomp_decompress(scomp, scratch->src, req->slen, - scratch->dst, &req->dlen, *ctx); + ret = crypto_scomp_decompress(scomp, src, req->slen, + dst, &req->dlen, *ctx); if (!ret) { if (!req->dst) { req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL); @@ -152,10 +165,19 @@ static int scomp_acomp_comp_decomp(struc ret = -ENOSPC; goto out; } - scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen, - 1); + if (dst == scratch->dst) { + scatterwalk_map_and_copy(scratch->dst, req->dst, 0, + req->dlen, 1); + } else { + flush_dcache_page(sg_page(req->dst)); + } } out: + if (src != scratch->src) + kunmap_local(src); + if (dst != scratch->dst) + kunmap_local(dst); + spin_unlock(&scratch->lock); return ret; } _ Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are zram-do-not-allocate-physically-contiguous-strm-buffers.patch crypto-introduce-acomp_is_sleepable-to-expose-if-comp-drivers-might-sleep.patch mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch