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fuse: avoid scheduling while atomic 

As reported by Richard Sharpe, an attempt to use fuse_notify_inval_entry()
triggers complains about scheduling while atomic:

  BUG: scheduling while atomic: fuse.hf/13976/0x10000001

This happens because fuse_notify_inval_entry() attempts to allocate memory
with GFP_KERNEL, holding "struct fuse_copy_state" mapped by kmap_atomic().

Introduced by commit 58bda1da4b "fuse/dev: use atomic maps"

Fix by moving the map/unmap to just cover the actual memcpy operation.

Original patch from Maxim Patlasov <mpatlasov@parallels.com>

Reported-by: Richard Sharpe <realrichardsharpe@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: <stable@vger.kernel.org> # v3.15+
This commit is contained in:
Miklos Szeredi 2014-07-07 15:28:51 +02:00
parent 233a01fa9c
commit c55a01d360
1 changed files with 23 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
fs/fuse/dev.c
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@ -643,9 +643,8 @@ struct fuse_copy_state {
unsigned long seglen;
unsigned long addr;
struct page *pg;
void *mapaddr;
void *buf;
unsigned len;
unsigned offset;
unsigned move_pages:1;
};
@ -666,23 +665,17 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
if (cs->currbuf) {
struct pipe_buffer *buf = cs->currbuf;
if (!cs->write) {
kunmap_atomic(cs->mapaddr);
} else {
kunmap_atomic(cs->mapaddr);
if (cs->write)
buf->len = PAGE_SIZE - cs->len;
}
cs->currbuf = NULL;
cs->mapaddr = NULL;
} else if (cs->mapaddr) {
kunmap_atomic(cs->mapaddr);
} else if (cs->pg) {
if (cs->write) {
flush_dcache_page(cs->pg);
set_page_dirty_lock(cs->pg);
}
put_page(cs->pg);
cs->mapaddr = NULL;
}
cs->pg = NULL;
}
/*
@ -691,7 +684,7 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
*/
static int fuse_copy_fill(struct fuse_copy_state *cs)
{
unsigned long offset;
struct page *page;
int err;
unlock_request(cs->fc, cs->req);
@ -706,14 +699,12 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
BUG_ON(!cs->nr_segs);
cs->currbuf = buf;
cs->mapaddr = kmap_atomic(buf->page);
cs->pg = buf->page;
cs->offset = buf->offset;
cs->len = buf->len;
cs->buf = cs->mapaddr + buf->offset;
cs->pipebufs++;
cs->nr_segs--;
} else {
struct page *page;
if (cs->nr_segs == cs->pipe->buffers)
return -EIO;
@ -726,8 +717,8 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
buf->len = 0;
cs->currbuf = buf;
cs->mapaddr = kmap_atomic(page);
cs->buf = cs->mapaddr;
cs->pg = page;
cs->offset = 0;
cs->len = PAGE_SIZE;
cs->pipebufs++;
cs->nr_segs++;
@ -740,14 +731,13 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
cs->iov++;
cs->nr_segs--;
}
err = get_user_pages_fast(cs->addr, 1, cs->write, &cs->pg);
err = get_user_pages_fast(cs->addr, 1, cs->write, &page);
if (err < 0)
return err;
BUG_ON(err != 1);
offset = cs->addr % PAGE_SIZE;
cs->mapaddr = kmap_atomic(cs->pg);
cs->buf = cs->mapaddr + offset;
cs->len = min(PAGE_SIZE - offset, cs->seglen);
cs->pg = page;
cs->offset = cs->addr % PAGE_SIZE;
cs->len = min(PAGE_SIZE - cs->offset, cs->seglen);
cs->seglen -= cs->len;
cs->addr += cs->len;
}
@ -760,15 +750,20 @@ static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
{
unsigned ncpy = min(*size, cs->len);
if (val) {
void *pgaddr = kmap_atomic(cs->pg);
void *buf = pgaddr + cs->offset;
if (cs->write)
memcpy(cs->buf, *val, ncpy);
memcpy(buf, *val, ncpy);
else
memcpy(*val, cs->buf, ncpy);
memcpy(*val, buf, ncpy);
kunmap_atomic(pgaddr);
*val += ncpy;
}
*size -= ncpy;
cs->len -= ncpy;
cs->buf += ncpy;
cs->offset += ncpy;
return ncpy;
}
@ -874,8 +869,8 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
out_fallback_unlock:
unlock_page(newpage);
out_fallback:
cs->mapaddr = kmap_atomic(buf->page);
cs->buf = cs->mapaddr + buf->offset;
cs->pg = buf->page;
cs->offset = buf->offset;
err = lock_request(cs->fc, cs->req);
if (err)