[PATCH net-next 1/3] net/smc: cap allocation order for SMC-R physically contiguous buffers
From: "D. Wythe" <alibuda@linux.alibaba.com>
Date: 2026-01-23 08:24:02
Also in:
linux-mm, linux-rdma, linux-s390, lkml
Subsystem:
networking [general], shared memory communications (smc) sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, D. Wythe, Dust Li, Sidraya Jayagond, Wenjia Zhang, Linus Torvalds
The alloc_page() cannot satisfy requests exceeding MAX_PAGE_ORDER, and attempting such allocations will lead to guaranteed failures and potential kernel warnings. For SMCR_PHYS_CONT_BUFS, the allocation order is now capped to MAX_PAGE_ORDER, ensures the attempts to allocate the largest possible physically contiguous chunk instead of failing with an invalid order, which also avoid redundant "try-fail-degrade" cycles in __smc_buf_create(). For SMCR_MIXED_BUFS, If it's order exceeds MAX_PAGE_ORDER, skips the doomed physical allocation attempt and fallback to virtual memory immediately. Signed-off-by: D. Wythe <alibuda@linux.alibaba.com> Reviewed-by: Dust Li <dust.li@linux.alibaba.com> --- net/smc/smc_core.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index e4eabc83719e..6219db498976 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c@@ -2324,26 +2324,30 @@ static struct smc_buf_desc *smcr_new_buf_create(struct smc_link_group *lgr, if (!buf_desc) return ERR_PTR(-ENOMEM); + buf_desc->order = get_order(bufsize); + switch (lgr->buf_type) { case SMCR_PHYS_CONT_BUFS: + buf_desc->order = min(buf_desc->order, MAX_PAGE_ORDER); + fallthrough; case SMCR_MIXED_BUFS: - buf_desc->order = get_order(bufsize); - buf_desc->pages = alloc_pages(GFP_KERNEL | __GFP_NOWARN | - __GFP_NOMEMALLOC | __GFP_COMP | - __GFP_NORETRY | __GFP_ZERO, - buf_desc->order); - if (buf_desc->pages) { - buf_desc->cpu_addr = - (void *)page_address(buf_desc->pages); - buf_desc->len = bufsize; - buf_desc->is_vm = false; - break; + if (buf_desc->order <= MAX_PAGE_ORDER) { + buf_desc->pages = alloc_pages(GFP_KERNEL | __GFP_NOWARN | + __GFP_NOMEMALLOC | __GFP_COMP | + __GFP_NORETRY | __GFP_ZERO, + buf_desc->order); + if (buf_desc->pages) { + buf_desc->cpu_addr = + (void *)page_address(buf_desc->pages); + buf_desc->len = bufsize; + buf_desc->is_vm = false; + break; + } } if (lgr->buf_type == SMCR_PHYS_CONT_BUFS) goto out; fallthrough; // try virtually contiguous buf case SMCR_VIRT_CONT_BUFS: - buf_desc->order = get_order(bufsize); buf_desc->cpu_addr = vzalloc(PAGE_SIZE << buf_desc->order); if (!buf_desc->cpu_addr) goto out;
--
2.45.0