This is a note to let you know that I've just added the patch titled mm/huge_memory: Fix xarray node memory leak to the 5.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-huge_memory-fix-xarray-node-memory-leak.patch and it can be found in the queue-5.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 69a37a8ba1b408a1c7616494aa7018e4b3844cbe Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Date: Wed, 8 Jun 2022 15:18:34 -0400 Subject: mm/huge_memory: Fix xarray node memory leak From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> commit 69a37a8ba1b408a1c7616494aa7018e4b3844cbe upstream. If xas_split_alloc() fails to allocate the necessary nodes to complete the xarray entry split, it sets the xa_state to -ENOMEM, which xas_nomem() then interprets as "Please allocate more memory", not as "Please free any unnecessary memory" (which was the intended outcome). It's confusing to use xas_nomem() to free memory in this context, so call xas_destroy() instead. Reported-by: syzbot+9e27a75a8c24f3fe75c1@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/xarray.h | 1 + lib/xarray.c | 5 +++-- mm/huge_memory.c | 3 +-- 3 files changed, 5 insertions(+), 4 deletions(-) --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -1508,6 +1508,7 @@ void *xas_find_marked(struct xa_state *, void xas_init_marks(const struct xa_state *); bool xas_nomem(struct xa_state *, gfp_t); +void xas_destroy(struct xa_state *); void xas_pause(struct xa_state *); void xas_create_range(struct xa_state *); --- a/lib/xarray.c +++ b/lib/xarray.c @@ -264,9 +264,10 @@ static void xa_node_free(struct xa_node * xas_destroy() - Free any resources allocated during the XArray operation. * @xas: XArray operation state. * - * This function is now internal-only. + * Most users will not need to call this function; it is called for you + * by xas_nomem(). */ -static void xas_destroy(struct xa_state *xas) +void xas_destroy(struct xa_state *xas) { struct xa_node *next, *node = xas->xa_alloc; --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2622,8 +2622,7 @@ out_unlock: if (mapping) i_mmap_unlock_read(mapping); out: - /* Free any memory we didn't use */ - xas_nomem(&xas, 0); + xas_destroy(&xas); count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); return ret; } Patches currently in stable-queue which might be from willy@xxxxxxxxxxxxx are queue-5.18/mm-huge_memory-fix-xarray-node-memory-leak.patch queue-5.18/block-make-bioset_exit-fully-resilient-against-being.patch queue-5.18/filemap-cache-the-value-of-vm_flags.patch