When the machine is under extreme memory pressure, the page_frag allocator signals this to the networking stack by marking allocations with the 'pfmemalloc' flag, which causes non-essential packets to be dropped. Unfortunately, even after the machine recovers from the low memory condition, the page continues to be used by the page_frag allocator, so all allocations from this page will continue to be dropped.
Fix this by freeing and re-allocating the page instead of recycling it. Reported-by: Dongli Zhang <[email protected]> Cc: Aruna Ramakrishna <[email protected]> Cc: Bert Barbe <[email protected]> Cc: Rama Nichanamatlu <[email protected]> Cc: Venkat Venkatsubra <[email protected]> Cc: Manjunath Patil <[email protected]> Cc: Joe Jin <[email protected]> Cc: SRINIVAS <[email protected]> Cc: [email protected] Fixes: 79930f5892e ("net: do not deplete pfmemalloc reserve") Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> --- mm/page_alloc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 778e815130a6..631546ae1c53 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5139,6 +5139,10 @@ void *page_frag_alloc(struct page_frag_cache *nc, if (!page_ref_sub_and_test(page, nc->pagecnt_bias)) goto refill; + if (nc->pfmemalloc) { + free_the_page(page, compound_order(page)); + goto refill; + } #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) /* if size can vary use size else just use PAGE_SIZE */ -- 2.28.0
