From: Hugh Dickins Date: Thu, 1 Dec 2005 20:21:57 +0000 (+0000) Subject: [SCSI] st: fix a bug in sgl_map_user_pages failure path X-Git-Tag: v2.6.15-rc5~14^2~2 X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=6bc733e9f71c937f3c64159bf1e569321726a44c;p=linux-2.6-omap-h63xx.git [SCSI] st: fix a bug in sgl_map_user_pages failure path Nick and I had already been looking at drivers/scsi/{sg.c,st.c}, brought there by __put_page in sg.c's peculiar sg_rb_correct4mmap, which we'd like to remove. But that's irrelevant to your pain, except... One extract from the patches I'd like to send Doug and Kai for 2.6.15 or 2.6.16 is this below: since the incomplete get_user_pages path omits to reset res, but has already released all the pages, it will result in premature freeing of user pages, and behaviour just like you've seen. Though I'd have thought incomplete get_user_pages was an exceptional case, and a bit surprised you'd encounter it. Perhaps there's some other premature freeing in the driver, and this instance has nothing whatever to do with it. If the problem were easily reproducible, it'd be great if you could try this patch; but I think you've said it's not :-( Signed-off-by: Kai Makisara Signed-off-by: James Bottomley --- diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c index 770c4324f3d..b1056d290ae 100644 --- a/drivers/scsi/st.c +++ b/drivers/scsi/st.c @@ -4509,6 +4509,7 @@ static int sgl_map_user_pages(struct scatterlist *sgl, const unsigned int max_pa if (res > 0) { for (j=0; j < res; j++) page_cache_release(pages[j]); + res = 0; } kfree(pages); return res;