On Tue, 30 Nov 2010, Boaz Harrosh wrote: > On 11/30/2010 06:23 PM, Kai Makisara wrote: > > On Tue, 30 Nov 2010, Boaz Harrosh wrote: > > > >> On 11/30/2010 03:31 PM, Lukas Kolbe wrote: > >>> On Mon, 2010-11-29 at 19:09 +0200, Kai Makisara wrote: > >>> > > .... > >> It looks like something is broken/old-code in sr. Most important LLDs > >> and block-layer scsi-ml fully support sg-chaining that effectively are > >> able to deliver limitless (Only limited by HW) sg sizes. It looks like > >> sr has some code that tries to allocate contiguous buffers larger than > >> PAGE_SIZE. Why does it do that? It should not be necessary any more. > >> > > The relevant driver is st > > Sorry I meant st, yes. > > > and it use sg chaining when necessary. I tried > > to explain that the effective limit in this case comes from mptsas. I > > don't know if it is HW limit or driver limit. > > > > Than I don't understand where is the failing allocation. Where in the > code path anyone is trying to allocate something bigger then a page? > Please explain? > The function enlarge_buffer() in st.c tries to allocate a driver buffer that is large enough for one block so that the number of contiguous memory blocks does not exceed the allowed maximum. Allocation is done using alloc_pages() (at line 3744 in st.c in 2.6.36), usually with order > 0. Kai -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
