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lib/scatterlist: Fix chaining support in sgl_alloc_order()

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This patch avoids that workloads with large block sizes (megabytes)
can trigger the following call stack with the ib_srpt driver (that
driver is the only driver that chains scatterlists allocated by
sgl_alloc_order()):

BUG: Bad page state in process kworker/0:1H  pfn:2423a78
page:fffffb03d08e9e00 count:-3 mapcount:0 mapping:          (null) index:0x0
flags: 0x57ffffc0000000()
raw: 0057ffffc0000000 0000000000000000 0000000000000000 fffffffdffffffff
raw: dead000000000100 dead000000000200 0000000000000000 0000000000000000
page dumped because: nonzero _count
CPU: 0 PID: 733 Comm: kworker/0:1H Tainted: G          I      4.15.0-rc7.bart+ #1
Hardware name: HP ProLiant DL380 G7, BIOS P67 08/16/2015
Workqueue: ib-comp-wq ib_cq_poll_work [ib_core]
Call Trace:
 dump_stack+0x5c/0x83
 bad_page+0xf5/0x10f
 get_page_from_freelist+0xa46/0x11b0
 __alloc_pages_nodemask+0x103/0x290
 sgl_alloc_order+0x101/0x180
 target_alloc_sgl+0x2c/0x40 [target_core_mod]
 srpt_alloc_rw_ctxs+0x173/0x2d0 [ib_srpt]
 srpt_handle_new_iu+0x61e/0x7f0 [ib_srpt]
 __ib_process_cq+0x55/0xa0 [ib_core]
 ib_cq_poll_work+0x1b/0x60 [ib_core]
 process_one_work+0x141/0x340
 worker_thread+0x47/0x3e0
 kthread+0xf5/0x130
 ret_from_fork+0x1f/0x30

Fixes: e80a0af475 ("lib/scatterlist: Introduce sgl_alloc() and sgl_free()")
Reported-by: Laurence Oberman <loberman@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche 2018-01-19 11:00:54 -08:00 • committed by Jens Axboe
parent 9b9c63f71b
commit 8c7a8d1c4b
3 changed files with 35 additions and 12 deletions
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2
drivers/target/target_core_transport.c
View file

@ -2300,7 +2300,7 @@ queue_full:
void target_free_sgl(struct scatterlist *sgl, int nents) void target_free_sgl(struct scatterlist *sgl, int nents)
{ {
sgl_free(sgl); sgl_free_n_order(sgl, nents, 0);
} }
EXPORT_SYMBOL(target_free_sgl); EXPORT_SYMBOL(target_free_sgl);

1
include/linux/scatterlist.h
View file

@ -282,6 +282,7 @@ struct scatterlist *sgl_alloc_order(unsigned long long length,
gfp_t gfp, unsigned int *nent_p); gfp_t gfp, unsigned int *nent_p);
struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
unsigned int *nent_p); unsigned int *nent_p);
void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
void sgl_free_order(struct scatterlist *sgl, int order); void sgl_free_order(struct scatterlist *sgl, int order);
void sgl_free(struct scatterlist *sgl); void sgl_free(struct scatterlist *sgl);
#endif /* CONFIG_SGL_ALLOC */ #endif /* CONFIG_SGL_ALLOC */

44
lib/scatterlist.c
View file

@ -512,7 +512,7 @@ struct scatterlist *sgl_alloc_order(unsigned long long length,
if (!sgl) if (!sgl)
return NULL; return NULL;
sg_init_table(sgl, nent); sg_init_table(sgl, nalloc);
sg = sgl; sg = sgl;
while (length) { while (length) {
elem_len = min_t(u64, length, PAGE_SIZE << order); elem_len = min_t(u64, length, PAGE_SIZE << order);
@ -526,7 +526,7 @@ struct scatterlist *sgl_alloc_order(unsigned long long length,
length -= elem_len; length -= elem_len;
sg = sg_next(sg); sg = sg_next(sg);
} }
WARN_ON_ONCE(sg); WARN_ONCE(length, "length = %lld\n", length);
if (nent_p) if (nent_p)
*nent_p = nent; *nent_p = nent;
return sgl; return sgl;
@ -548,6 +548,36 @@ struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
} }
EXPORT_SYMBOL(sgl_alloc); EXPORT_SYMBOL(sgl_alloc);
/**
* sgl_free_n_order - free a scatterlist and its pages
* @sgl: Scatterlist with one or more elements
* @nents: Maximum number of elements to free
* @order: Second argument for __free_pages()
*
* Notes:
* - If several scatterlists have been chained and each chain element is
* freed separately then it's essential to set nents correctly to avoid that a
* page would get freed twice.
* - All pages in a chained scatterlist can be freed at once by setting @nents
* to a high number.
*/
void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
{
struct scatterlist *sg;
struct page *page;
int i;
for_each_sg(sgl, sg, nents, i) {
if (!sg)
break;
page = sg_page(sg);
if (page)
__free_pages(page, order);
}
kfree(sgl);
}
EXPORT_SYMBOL(sgl_free_n_order);
/** /**
* sgl_free_order - free a scatterlist and its pages * sgl_free_order - free a scatterlist and its pages
* @sgl: Scatterlist with one or more elements * @sgl: Scatterlist with one or more elements
@ -555,15 +585,7 @@ EXPORT_SYMBOL(sgl_alloc);
*/ */
void sgl_free_order(struct scatterlist *sgl, int order) void sgl_free_order(struct scatterlist *sgl, int order)
{ {
struct scatterlist *sg; sgl_free_n_order(sgl, INT_MAX, order);
struct page *page;
for (sg = sgl; sg; sg = sg_next(sg)) {
page = sg_page(sg);
if (page)
__free_pages(page, order);
}
kfree(sgl);
} }
EXPORT_SYMBOL(sgl_free_order); EXPORT_SYMBOL(sgl_free_order);