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ublk: fix maple tree lockdep warning and unpin under spinlock #761

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ublk: fix maple tree lockdep warning and unpin under spinlock #761

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63 changes: 39 additions & 24 deletions drivers/block/ublk_drv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5413,16 +5413,39 @@ static int ublk_ctrl_reg_buf(struct ublk_device *ub,
return ret;
}

static void ublk_unpin_range_pages(unsigned long base_pfn,
unsigned long nr_pages)
{
#define UBLK_UNPIN_BATCH 32
struct page *pages[UBLK_UNPIN_BATCH];
unsigned long off;

for (off = 0; off < nr_pages; ) {
unsigned int batch = min_t(unsigned long,
nr_pages - off, UBLK_UNPIN_BATCH);
unsigned int j;

for (j = 0; j < batch; j++)
pages[j] = pfn_to_page(base_pfn + off + j);
unpin_user_pages(pages, batch);
off += batch;
}
}

/*
* Drop mas_lock during iteration to avoid unpinning pages under spinlock.
* Safe because callers hold ub->mutex (via ublk_lock_buf_tree), preventing
* concurrent tree modifications.
*/
static int __ublk_ctrl_unreg_buf(struct ublk_device *ub, int buf_index)
{
MA_STATE(mas, &ub->buf_tree, 0, ULONG_MAX);
struct ublk_buf_range *range;
struct page *pages[32];
int ret = -ENOENT;

mas_lock(&mas);
mas_for_each(&mas, range, ULONG_MAX) {
unsigned long base, nr, off;
unsigned long base, nr;

if (range->buf_index != buf_index)
continue;
Expand All @@ -5431,18 +5454,12 @@ static int __ublk_ctrl_unreg_buf(struct ublk_device *ub, int buf_index)
base = mas.index;
nr = mas.last - base + 1;
mas_erase(&mas);
mas_unlock(&mas);

for (off = 0; off < nr; ) {
unsigned int batch = min_t(unsigned long,
nr - off, 32);
unsigned int j;

for (j = 0; j < batch; j++)
pages[j] = pfn_to_page(base + off + j);
unpin_user_pages(pages, batch);
off += batch;
}
ublk_unpin_range_pages(base, nr);
kfree(range);

mas_lock(&mas);
}
mas_unlock(&mas);

Expand Down Expand Up @@ -5472,29 +5489,27 @@ static int ublk_ctrl_unreg_buf(struct ublk_device *ub,
return ret;
}

/*
* Drop mas_lock during iteration to avoid unpinning pages under spinlock.
* Safe because this is called from device release with exclusive access.
*/
static void ublk_buf_cleanup(struct ublk_device *ub)
{
MA_STATE(mas, &ub->buf_tree, 0, ULONG_MAX);
struct ublk_buf_range *range;
struct page *pages[32];

mas_lock(&mas);
mas_for_each(&mas, range, ULONG_MAX) {
unsigned long base = mas.index;
unsigned long nr = mas.last - base + 1;
unsigned long off;

for (off = 0; off < nr; ) {
unsigned int batch = min_t(unsigned long,
nr - off, 32);
unsigned int j;

for (j = 0; j < batch; j++)
pages[j] = pfn_to_page(base + off + j);
unpin_user_pages(pages, batch);
off += batch;
}
mas_erase(&mas);
mas_unlock(&mas);
ublk_unpin_range_pages(base, nr);
kfree(range);
mas_lock(&mas);
}
mas_unlock(&mas);
mtree_destroy(&ub->buf_tree);
ida_destroy(&ub->buf_ida);
}
Expand Down