Messages in this thread | | | Date | Wed, 17 Aug 2022 21:24:44 +0300 | Subject | Re: [PATCH] nvmet-tcp: Don't kmap() pages which can't come from HIGHMEM | From | Sagi Grimberg <> |
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>> @@ -329,7 +312,6 @@ static void nvmet_tcp_map_pdu_iovec(struct nvmet_tcp_cmd *cmd) >> u32 length, offset, sg_offset; >> >> length = cmd->pdu_len; >> - cmd->nr_mapped = DIV_ROUND_UP(length, PAGE_SIZE); >> offset = cmd->rbytes_done; >> cmd->sg_idx = offset / PAGE_SIZE; >> sg_offset = offset % PAGE_SIZE; >> @@ -338,7 +320,7 @@ static void nvmet_tcp_map_pdu_iovec(struct nvmet_tcp_cmd *cmd) >> while (length) { >> u32 iov_len = min_t(u32, length, sg->length - sg_offset); >> >> - iov->iov_base = kmap(sg_page(sg)) + sg->offset + sg_offset; >> + iov->iov_base = page_address(sg_page(sg)) + sg->offset + sg_offset; >> iov->iov_len = iov_len; >> >> length -= iov_len; >> @@ -347,8 +329,7 @@ static void nvmet_tcp_map_pdu_iovec(struct nvmet_tcp_cmd *cmd) >> sg_offset = 0; >> } >> >> - iov_iter_kvec(&cmd->recv_msg.msg_iter, READ, cmd->iov, >> - cmd->nr_mapped, cmd->pdu_len); >> + iov_iter_kvec(&cmd->recv_msg.msg_iter, READ, cmd->iov, 0, cmd->pdu_len); >> } > > I earlier meant just use a local variable for 'nr_mapped' rather than replace > it with '0'. I don't think that 0 segments would result in usable kvec.
yes, that is wrong. Need a local int nr_mapped variable.
> > I'm not even sure the existing code is correct, though. The sg->length can be > higher order than a PAGE_SIZE, so it may be over-reporting nr_segs. It's just > supposed to be the number of initialized iov's.
The sg is allocated with sgl_alloc so it is for sure 0-order.
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