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wrote: > From: Hao Ge > > If two competing threads enter alloc_slab_obj_exts() and one of them > fails to allocate the object extension vector, it might override the > valid slab->obj_exts allocated by the other thread with > OBJEXTS_ALLOC_FAIL. This will cause the thread that lost this race and > expects a valid pointer to dereference a NULL pointer later on. > > Update slab->obj_exts atomically using cmpxchg() to avoid > slab->obj_exts overrides by racing threads. > > Thanks for Vlastimil and Suren's help with debugging. > > Fixes: f7381b911640 ("slab: mark slab->obj_exts allocation failures unconditionally") > Cc: > Suggested-by: Suren Baghdasaryan > Signed-off-by: Hao Ge > --- > v3: According to Suren's suggestion, simplify the commit message and the code comments. > Thanks for Suren. > > v2: Incorporate handling for the scenario where, if mark_failed_objexts_alloc wins the race, > the other process (that previously succeeded in allocation) will lose the race, based on Suren's suggestion. > Add Suggested-by: Suren Baghdasaryan > --- Looks good to me, thanks for fixing this! Reviewed-by: Harry Yoo -- Cheers, Harry / Hyeonggon