Messages in this thread | | | Date | Mon, 25 Apr 2005 19:02:59 +0200 | From | Olivier Galibert <> | Subject | tcp_sendpage and page allocation lifetime vs. iscsi |
| |
I have a problem with the iscsi driver (both 4.x and 5.x) and scsi tape I'm not sure how to solve. It may linked to some specific characteristics of the tg3 network driver.
What happens is, from what I can trace: 1- st alloc_pages a bunch of pages for buffering
2- st sends a bunch of them to iscsi for writing (32K is common when labelling a tape for instance)
3- iscsi sends whatever header is needed followed by the data using tcp_sendpage
4- tcp_sendpage copies from of the pages but get_page() others, probably depending on the state of the socket buffer. It returns immediatly anyway, leaving some pages with an elevated count (which, I guess, it will eventually decrement again)
5- iscsi returns to st
6- st reuses the buffer immediatly, and/or frees it if the device is closed. Silent corruption in one case, bad_page in __free_page_ok called from normalize_buffer in the other.
I'm going to complete my traces to be sure that's really what's going on (I don't have a log immediatly after sendpage yet). But in any case, what would the solution be?
OG.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |