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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:
parent
233a01fa9c
commit
c55a01d360
1 changed files with 23 additions and 28 deletions
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@ -643,9 +643,8 @@ struct fuse_copy_state {
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unsigned long seglen;
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unsigned long addr;
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struct page *pg;
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void *mapaddr;
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void *buf;
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unsigned len;
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unsigned offset;
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unsigned move_pages:1;
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};
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@ -666,23 +665,17 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
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if (cs->currbuf) {
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struct pipe_buffer *buf = cs->currbuf;
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if (!cs->write) {
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kunmap_atomic(cs->mapaddr);
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} else {
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kunmap_atomic(cs->mapaddr);
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if (cs->write)
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buf->len = PAGE_SIZE - cs->len;
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}
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cs->currbuf = NULL;
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cs->mapaddr = NULL;
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} else if (cs->mapaddr) {
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kunmap_atomic(cs->mapaddr);
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} else if (cs->pg) {
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if (cs->write) {
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flush_dcache_page(cs->pg);
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set_page_dirty_lock(cs->pg);
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}
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put_page(cs->pg);
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cs->mapaddr = NULL;
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}
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cs->pg = NULL;
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}
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/*
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@ -691,7 +684,7 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
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*/
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static int fuse_copy_fill(struct fuse_copy_state *cs)
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{
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unsigned long offset;
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struct page *page;
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int err;
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unlock_request(cs->fc, cs->req);
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@ -706,14 +699,12 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
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BUG_ON(!cs->nr_segs);
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cs->currbuf = buf;
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cs->mapaddr = kmap_atomic(buf->page);
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cs->pg = buf->page;
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cs->offset = buf->offset;
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cs->len = buf->len;
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cs->buf = cs->mapaddr + buf->offset;
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cs->pipebufs++;
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cs->nr_segs--;
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} else {
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struct page *page;
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if (cs->nr_segs == cs->pipe->buffers)
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return -EIO;
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@ -726,8 +717,8 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
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buf->len = 0;
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cs->currbuf = buf;
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cs->mapaddr = kmap_atomic(page);
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cs->buf = cs->mapaddr;
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cs->pg = page;
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cs->offset = 0;
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cs->len = PAGE_SIZE;
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cs->pipebufs++;
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cs->nr_segs++;
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@ -740,14 +731,13 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
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cs->iov++;
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cs->nr_segs--;
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}
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err = get_user_pages_fast(cs->addr, 1, cs->write, &cs->pg);
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err = get_user_pages_fast(cs->addr, 1, cs->write, &page);
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if (err < 0)
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return err;
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BUG_ON(err != 1);
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offset = cs->addr % PAGE_SIZE;
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cs->mapaddr = kmap_atomic(cs->pg);
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cs->buf = cs->mapaddr + offset;
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cs->len = min(PAGE_SIZE - offset, cs->seglen);
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cs->pg = page;
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cs->offset = cs->addr % PAGE_SIZE;
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cs->len = min(PAGE_SIZE - cs->offset, cs->seglen);
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cs->seglen -= cs->len;
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cs->addr += cs->len;
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}
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@ -760,15 +750,20 @@ static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
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{
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unsigned ncpy = min(*size, cs->len);
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if (val) {
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void *pgaddr = kmap_atomic(cs->pg);
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void *buf = pgaddr + cs->offset;
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if (cs->write)
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memcpy(cs->buf, *val, ncpy);
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memcpy(buf, *val, ncpy);
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else
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memcpy(*val, cs->buf, ncpy);
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memcpy(*val, buf, ncpy);
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kunmap_atomic(pgaddr);
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*val += ncpy;
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}
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*size -= ncpy;
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cs->len -= ncpy;
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cs->buf += ncpy;
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cs->offset += ncpy;
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return ncpy;
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}
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@ -874,8 +869,8 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
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out_fallback_unlock:
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unlock_page(newpage);
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out_fallback:
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cs->mapaddr = kmap_atomic(buf->page);
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cs->buf = cs->mapaddr + buf->offset;
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cs->pg = buf->page;
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cs->offset = buf->offset;
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err = lock_request(cs->fc, cs->req);
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if (err)
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