Messages in this thread | | | Date | Fri, 7 Aug 2009 10:26:32 -0400 | From | Josh Boyer <> | Subject | Re: [UBI UBIFS] replace vmalloc with kmalloc |
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On Fri, Aug 07, 2009 at 12:20:03PM +0300, Adrian Hunter wrote: > JiSheng Zhang wrote: >> If nandflash driver use DMA to support UBI and UBIFS i/o, there will >> be panic like >> the following. This is because UBI and UBIFS use vmalloced buffer >> somewhere while >> nandflash driver put the buffer under DMA and DMA support doesn't like vmalloced >> memory. >> [ 412.369280] UBIFS: default file-system created >> [ 412.374879] Unable to handle kernel NULL pointer dereference at >> virtual address 00000000 >> [ 412.383177] UBIFS: background thread "ubifs_bgt0_0" started, PID 887 >> [ 412.389656] pgd = c0004000 >> [ 412.392419] [00000000] *pgd=00000000 >> [ 412.396117] Internal error: Oops: 817 [#1] PREEMPT >> >> Yes, I know kmalloc may fail when memory get fragmented, but I grep the UBI and >> UBIFS's source, there are six .c files and seven .c files using >> vmalloc, the function >> which call vmalloc are all called during the ubi being attached and >> the volume being >> mounted. In embedded system, this mainly happen during kernel boot, it >> should succeed. >> >> After replacing vmalloc with kmalloc, ubi and ubifs runs fine on my >> board. I can alos upload >> a patch. >> >> Comments are welcomed! > > vmalloc allows large (> 128KiB) buffers, but kmalloc doesn't. > So we presently have no choice but to use vmalloc.
You could use get_free_pages to get up to 2MiB, no?
josh
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